Any quality difference of tracks between DJ pools and online stores?

If you are serious about being an audiophile, get out of DJ-ing LOL. At the very least separate private, audiophile listening and it’s tracks from your DJ collection.

320MP3 or 256AAC (Apple) are perfectly suitable for playing over PA systems. There is, however, a good reason for buying lossless (WAV, FLAC, AIFF). There is a good chance you will want to do stuff to your tracks during preparation and it’s beter to do all work on a lossless format and only convert to MP3 at the end just before putting the tracks in your DJ software. Or, if you have the diskspace you could keep them uncompressed, unfortunately tracks in WAV format for example have relatively mediocre tagging options.

Not necessarily. The whole problem is that you never get guarantees. They can sell you a 256MP3, but you never know what the source was. Or even worse a 320MP3. There have been instances where it is clear that the source definitely was not losless, i.e. the original track.

If you buy from reputable houses like Beatport Pro for example and you get the full WAV version, you do pay more, but (hopefully) you can be sure to get a full uncompressed version.

At the end of the day, opposed to CDs, there is absolutely no way you, as end-user, can ascertain what the source quality is of any track you buy online. And as far as I know there is on easy way to check a wav, flac or AIFF file to see if it is just a reconverted track (MP3 back to WAV, it happens) or an original track.

At the end of the day, the old adagio “trust your ears” is still valid. If you download it, listen to it on decent speakers, perhaps A/B compare it to some tracks in the same genre that you know come from reputable sources (like CDs you have bought and ripped to WAV yourself) and then decide if the quality matches what you expect it to be or not.

This really does touch on one of the major drawbacks to single track online purchases.

Perhaps there should be something like a quality mark by an independent organisation where an online outlet can get accreditation by proving the source of their tracks.

Good stuff Chris.