Samplerates: The Higher the Better, Right?

This is largely because MP3 is a crappy, old format. Try high-bitrate Opus on most samples and you're a lot less likely to get above-chance results on an ABX test, pretty much ever, at high bitrates. Ultimately though, lossy compression is always program-dependent ("program" here means the song, not the app). The encoders use psychoacoustic algorithms, and there is no way to prove they will perform well on all samples. So you will always be able to find corner cases where an encoder or format does worse and results in more audible artifacts; some of these might be encoder bugs, some might not. Therefore, it is fair to say that you might not want to rely on lossy compression for archival. But it is perfectly reasonable to use it to put music on devices to actually listen to. You say good mastering makes it easier to notice encoding artifacts, but actually, bad mastering can do that too. Over-compressed stuff (in dynamic range) with inter-sample peaks above 0dB can clip and distort after getting run through a lossy codec. As for lossless formats, though, anything above 48kHz 16 bits is complete nonsense for final delivery to consumers. All the "high resolution" stuff with higher sample rates and bit depths is just marketing bullshit, and this has been repeatedly demonstrated in trials (the well-designed ones anyway; there are plenty of terrible ones - no, comparing the 96kHz download to the 48kHz download of a song is not how you test this properly). Bit depths above 16 are use