Sources: analog and digital

What a source does

A source's job is to hand the amplifier a clean line-level signal — a small analogue voltage carrying the shape of the music. What varies is how that signal is stored and how much processing stands between the stored data and that voltage.

Digital sources — streaming and CD — store numbers, so somewhere a digital-to-analogue converter (DAC) has to turn those numbers back into a voltage. Vinyl skips that entirely: the groove is already an analogue copy of the waveform, so the signal is analogue from the needle onward. That single distinction explains most of the character differences people hear between the formats.

Where the DAC physically lives varies: inside a network streamer, inside a CD player, built into a streaming amplifier, inside an active speaker, or in a separate box of its own. The conversion has to happen once, and modern DACs do it extremely well — the debate over which source "sounds best" is far less about the converter than most marketing implies.

Streaming: the default source

For most people building a system today, streaming is the source. A network streamer (or the streaming section of an all-in-one amplifier) pulls audio over your home network from a service or a local library, decodes it, and feeds a DAC. The appeal is obvious: tens of millions of tracks, no shelf space, and a phone as the remote.

The one thing worth understanding is quality tiers, because not all streaming is the same:

• Lossy — the audio is compressed by throwing away data the format's designers judged inaudible. Spotify tops out here at 320 kbps, and it is genuinely good; most listeners can't reliably tell 320 kbps from lossless on most music. This is compression in the data sense, nothing to do with an amplifier's compression.
• Lossless, CD-quality — a perfect 16-bit/44.1 kHz copy, bit-for-bit identical to the CD, in a format like FLAC or ALAC. Apple Music, Tidal, Qobuz and Amazon Music all offer this. This is the sensible target: transparent, and the file the vast majority of music is actually mastered to.
• Hi-res — 24-bit files at 96 or 192 kHz. The extra bits and bandwidth are real, but see the reality check further down: their audible benefit on playback is small and much debated. Useful mainly as evidence you're getting the best available master.

A few practical notes. Roon is popular library-and-playback software that unifies your local files and streaming services behind one polished interface — several streamers advertise "Roon Ready" certification for it. MQA, a hi-res codec pushed hard around 2018, has faded: its parent company entered administration in 2023 and Tidal, its biggest backer, moved to standard hi-res FLAC. And Bluetooth is a source too, but a compromised one — even the better codecs (aptX HD, LDAC) are lossy, so it's for convenience, not critical listening.

Several brands in this catalog build streaming sources or amplifiers with streaming built in — Cambridge Audio, Marantz, Arcam, Rega, T+A, McIntosh and PS Audio among them. And the active, network-connected speakers from Devialet, Bang & Olufsen, Dutch & Dutch and Kii Audio fold the streamer, DAC and amplifier into the speaker itself.

The DAC, and what bit depth and sample rate mean

Digital audio is described by two numbers, and they measure different things:

• Sample rate (kHz) — how many times per second the waveform's level was measured. CD is 44.1 kHz. By the sampling theorem, a 44.1 kHz rate perfectly captures every frequency up to 22.05 kHz, which is already above the ~20 kHz ceiling of adult human hearing. Higher rates (96, 192 kHz) extend that, but into ultrasound.
• Bit depth (bits) — how finely each measurement is resolved, which sets the dynamic range between the quietest and loudest possible sound. 16 bits gives about 96 dB of range; 24 bits gives about 144 dB — more than any room's noise floor and playback level can ever use.

What actually matters in a DAC is not chasing ever-bigger numbers but clean execution: low noise, low distortion and low jitter (timing errors in the conversion). Competent modern DACs — from a $200 streamer up — are essentially transparent by these measures. This is why swapping a good DAC for a more expensive good DAC rarely produces the night-and-day change the price gap implies.

The CD: the format everyone underrates

The compact disc arrived in 1982 carrying 16-bit/44.1 kHz audio — the "Red Book" standard — and that specification, chosen four decades ago, is still enough to be sonically transparent for playback. A CD holds a bit-perfect copy of the master at CD quality; a streamed lossless track is, at best, exactly the same data delivered over the internet.

A CD player does two jobs: a transport reads the disc, and a DAC converts the data. Because reading a CD is a low-error, well-understood process, the transport matters far less than folklore claims — the DAC and analogue output stage are where players differ. Many listeners now use a CD player mainly to rip their discs to lossless files once, then stream those files, getting the archival permanence of physical media with the convenience of a library.

The CD's commercial decline is real, but a physical, DRM-free, genuinely lossless format that you own outright — and that often sells used for pocket change — has an obvious appeal in the streaming age. In this catalog Marantz, Cambridge Audio, Rega, Arcam and McIntosh all still make CD players.

Vinyl: the analogue ritual

Vinyl is the odd one out and the reason is physical: the groove is a direct mechanical analogue of the waveform, so there is no sampling and no conversion. A stylus traces the groove, a cartridge turns that motion into a tiny electrical signal, and that signal is amplified and played. People don't choose vinyl because it measures better — it measures worse than CD on almost every axis — they choose it for the sound's character and the ritual of playing a record.

A vinyl front end is a small system in itself, and every part interacts:

• Turntable — spins the record at a precise, steady speed. The two motor designs are belt drive (a belt isolates motor vibration; common in hi-fi) and direct drive (the platter is the motor; instant speed and the DJ standard, epitomised by the Technics SL-1200).
• Tonearm — holds the cartridge at the right angle and tracking force and lets it follow the groove across the disc. Its mass has to be matched to the cartridge's compliance.
• Cartridge — the transducer at the tip. Moving magnet (MM) cartridges are affordable, robust and have a user-replaceable stylus; moving coil (MC) cartridges cost more, generally resolve more detail, and output a far smaller signal that needs more gain.
• Phono stage — a specialised preamp that boosts the cartridge's tiny signal and applies the RIAA equalisation curve. It's mandatory: records are cut with the bass reduced and the treble boosted, and the phono stage reverses that. A regular line input can't play a turntable.

Vinyl rewards setup like no other source. Tracking force, anti-skate and cartridge alignment all have to be right, or you get distortion and accelerated record wear. That fiddliness is part of the appeal for some and a dealbreaker for others. Turntable makers in this catalog include Rega (the belt-drive Planar series), Technics (the direct-drive SL-1200 lineage) and MoFi; Cambridge Audio, Rega and others also make standalone phono stages.

Tape: cassette and reel-to-reel

Tape is the other analogue format, and like vinyl it stores the waveform physically — as a pattern of magnetism on a plastic ribbon rather than a groove in a disc. A tape deck's head reads that magnetism and turns it back into a signal. It shares vinyl's analogue character and adds two signatures of its own: a faint background hiss, and wow and flutter — small speed variations that smear pitch slightly.

• Compact cassette — the ubiquitous format of the 1970s–90s. Modest fidelity, but it invented the personal, recordable mixtape, and it's in the middle of a genuine collectors' revival. Sound quality depends heavily on the tape type (Type I ferric up to Type IV metal) and on Dolby noise reduction to tame the hiss. Good decks are now sought-after used items, as the format is no longer manufactured at the high end.
• Reel-to-reel (open reel) — the professional ancestor, running wider tape much faster. At its best it's the highest-fidelity analogue format there is — it is what studio master tapes were recorded on — and a small audiophile scene trades tape copies of masters at a steep price. Big, heavy, expensive machines, and a niche within a niche.

Radio: FM, DAB and internet

Broadcast radio is the oldest source of all, and still a way to discover music that no algorithm curates. It reaches a system in three ways:

• FM — analogue broadcast, and a good FM station with a decent tuner and antenna can sound genuinely excellent. This is why so many classic amplifiers were receivers: an integrated amplifier with a tuner built in.
• DAB / DAB+ — digital broadcast, common in Europe and elsewhere. More stations and no analogue hiss, though heavily compressed streams can sound worse than a strong FM signal, not better.
• Internet radio — thousands of stations streamed over your network, built into most network streamers and all-in-one amplifiers. No tuner or antenna required; it's really just another thing the streamer does.

Standalone tuners have become rare, but several names in this catalog built famous ones in the FM era — Marantz, Leak, Quad and McIntosh among them — and the tuner still turns up inside receivers and all-in-ones from makers like Cambridge Audio and Arcam.

The computer, and the disc formats beyond CD

A few more sources round out the picture, most of them digital variations on ground already covered:

• Computer as a source. A PC, Mac, phone or tablet feeding a USB DAC is a serious source — with asynchronous USB the DAC controls the timing, so a bit-perfect file plays back with no penalty for coming from a computer. It's also the natural home for a large local library of ripped and downloaded files.
• High-resolution downloads. Bought as files (FLAC, ALAC, WAV) from stores like Qobuz or Bandcamp, these are the download equivalent of hi-res streaming — you own them outright, and the same reality check applies: chase the master, not the sample rate.
• SACD and DSD. The Super Audio CD was the CD's would-be hi-res successor, using the DSD encoding still used for some downloads. It never went mainstream but has a devoted following, and hybrid discs also carry a normal CD layer. Marantz and McIntosh still make SACD players.
• The historical footnotes. MiniDisc, DAT, DVD-Audio and the 8-track cartridge all had their moment and faded. You'll meet them secondhand rather than new, and mostly as curiosities.

The hi-res reality check

It's worth stating plainly, because a lot of money rides on it: for playback, 16-bit/44.1 kHz — plain CD quality — already covers the entire audible band with dynamic range no listening room can exhaust. Controlled listening tests have repeatedly failed to show a reliable audible advantage for hi-res files over a good CD-quality version of the same master.

Which is not to say hi-res is pointless. The extra headroom genuinely matters during production (recording and mixing), and a hi-res release is often simply a better, more careful master than the old CD — and it's the master, far more than the format, that you actually hear. So the honest advice is: chase the good master, not the big numbers, and don't let a lack of hi-res stop you enjoying music.

Which source is right for you

There is no single best source — the formats optimise for different things:

• Choose streaming for reach and convenience: everything ever recorded, instantly, controlled from your phone. Pick a service with a lossless (CD-quality) tier and you give up essentially nothing in sound. This is the right default for most new systems.
• Choose CD if you want to own your music outright in a lossless, DRM-free form, value a physical collection, or buy a lot of music secondhand. Rip once and you also get a local library.
• Choose vinyl for the experience — the sleeves, the ritual, and a sound whose warmth and imperfection you actively enjoy. Go in knowing it costs more per album, needs careful setup, and is the least accurate of the three. Those aren't flaws to fix; they're the point.

Plenty of systems run two or three of these at once — a streamer for everyday listening, a turntable for records, a CD player for the collection — feeding the same amplifier and speakers. The source is only the first link, though: what you feed it into decides how much of its quality survives. From here, read Amplifiers explained for the box in the middle, Active vs passive speakers for systems that build the source and amplifier into the speaker, and put your speaker shortlist side by side at true scale in TrueScale.