Best File Format These Days

It’s all about the metadata and third party device support, hence FLAC.


Sorry to revisit what is likely a dead topic, but could someone give me the best suggestion here if you were doing your library again?

I’m re-ripping my 3000 CD’s on my Small Green Computer Linux-based server with 4TB of local SSD disk. Roon is running on a separate local SSD. My endpoint and DAC is the PS Audio DSJ and I’m directly connected via ethernet cable.

For all these regular CD’s should I just use FLAC? I would like the best sound quality and I want my library to be future-proof.

Looks like the default option is FLAC but it gives me a choice between FLAC uncompressed and FLAC compressed. Is there any difference?

Many thanks…


flagging @agillis

With Roon doing the decoding to PCM and sending it to a separate ethernet endpoint, use maximum compression (FLAC level 8) to save space. It sounds identical to WAV here on my BDP-1. Your endpoint sees the same thing regardless of what you start out with (ALAC, FLAC compressed/uncompressed, WAV, AIFF).

FLAC for everything. The only difference is file size. I use Level 3 which is slight compression. Typical level is 5, but if filesize is less of an issue, use uncompressed. You can always recompress at any level later - completely losslessly.

1 Like

I still prefer a lossless uncompressed file vs. a lossless compressed file:

As @zoom25 says, using a lossless compressed format like FLAC or ALAC compared to an uncompressed format makes ZERO difference with Roon when using an endpoint. To my ears, it makes no difference when using my computer directly with Roon or Audirvana. Don’t let expectation bias get the best of you here…

That’s one opinion. There are just as many if not more opinions in the opposite direction. Have you ever wondered why professional recording and mastering studios only use uncompressed and never compressed files? Literally no pros use compressed files at all.

Also see: aiff

Because they need to operate on the files. It makes a lot more sense to keep those files uncompressed rather than have to uncompress, process, and recompress all the time. It makes no difference to the bits, though. For storage, it makes a ton more sense to compress the files since they’ll just end up eating way more space than necessary uncompressed.

This is not just highly questionable, but also way out of date. Endianness is a property of the CPU, not the operating system; and since the switch to Intel, Macs are just as Little-Endian as Windows. Being able to hear endianness is pretty laughable, even by audiophile standards.

You can’t argue for any difference in SQ between any lossless formats when the network endpoint receives identical PCM.

If your endpoint was the one decoding and converting the WAV or FLAC to PCM within the endpoint itself, then you could at least make some argument that the work load is different between FLAC or WAV which may result in different SQ.

However, with Roon endpoints the computer (iMac in my case) converts the ALAC, FLAC, AIFF, and WAV to PCM before it leaves the computer. It’s sending PCM on the network. So the only thing that your endpoint ever sees with Roon is PCM. The network endpoint never sees FLAC or WAV. This is why there cannot be a difference in SQ between any of the lossless formats. PCM = PCM, regardless of how it was derived. This deriving process is completely isolated from the final endpoint.

There is simply no mechanism by which Roon ‘NETWORKED’ endpoints can sound different depending on what type of lossless file is processed inside the Roon Core.

As I’ve stated before, with USB DACs or players where the decoding to PCM takes place inside the player, there is at least a mechanism by which you can explain why these formats may sound different. That mechanism simply doesn’t exist with NETWORKED endpoints…unless you are claiming that the networked endpoint can tell difference between two identical PCM streams because of how they were derived.

1 Like

If you’ve been working with DAWs and multiple tracks for a long time, the answer will be very obvious from a practical standpoint. It has nothing to do with SQ as you may think and/or may be implying.

1 Like

Quite right. It has to do with where a number’s most significant digit is placed, either in the upper or lower half word. The type of endian stream is only a problem when porting code between the two different types. Even then, unless one is bit twiddling, a recompile takes care of the problem. It’s never a problem about data interpretation.

I don’t run a Roon network, I play Roon directly on the Mac, and hear a difference between uncompressed and compressed files. In the end, it’s easy enough for one to do a comparison themselves, blind or otherwise. Just play the same track as a WAV or AIFF and then play it as an ALAC and listen for yourself. If you hear no difference, congrats, you will save some hard drive space (although that’s a bit of a non-issue these days given that hard disks are so cheap).

Just because it’s ALAC doesn’t mean it isn’t lossy. The ALAC file extension come in both flavors. Are you sure the ALAC file you’re comparing is lossless?

Probably the better comparison would be WAV vs. FLAC. Ever try that?

1 Like

So you are running Roon on a Mac…with your DAC connected by USB directly to the Mac?

ALAC = Apple Lossless Audio Codec.

I’ve never seen a lossy ALAC. As long as the converter is legit, you can go back and forth between all of these lossless formats.

This is correct.

I love FLAC because it’s so compatible almost everything support it now. Although it’s lossless it has great compression usually about 40%.

The uncompressed FLAC option is actually a WAV file with a FLAC header.

Some audiophile still prefer WAV files. This is because WAV files do actually sound better on some older streaming audio equipment.

If you are using a sonicTransporter as a Roon server and a ultraRendu attached to your USB DAC go with standard FLAC. It will sound great. There will be no difference in sound with a modern setup like this.

If you have some other music playback equipment it’s not a bad idea to test both an see if it makes a difference.

Good to get some clarity. As I’ve said, with direct USB connection all bets are off, but with networked devices and Roon doing the decoding, there simply is no mechanism. I’ve done the FLAC and WAV test on many hardware players and software applications that all handle decoding and buffering differently.

Try this test. Have Roon running and setup. Quit everything. Turn off Wifi. Open Activity Monitor if needed so you can see some numbers. Start playing music and get used to the sound. Turn on the wifi and see if you notice a difference when it’s turned on. Next, open Safari and load up Youtube. Start playing a 1080p or 4k Video with the audio muted. Do you notice a difference in sound through any of these steps?

You can do this sighted or have anyone else do this for you at any point. Go ahead and try this sighed and report back. It takes max 2 mins.

@xxx. Are you sure you’re not talking about AAC? That is Apple’s Lossy codec.

ALAC is only data compressed (Just like FLAC), there is no lossy audio compression and to my ears it sounds identical to FLAC, WAV and AIFF.