One thing to check is that the files provenance is trustworthy. Maybe start with AIX recordings and mp3-ify them yourself..
What kind of amps can you easily tell the difference between? Headphone? Speaker? Solid-state vs tube?
For me, with DACs, some I can listen to for hours and others, not so much.
The FLAC files were converted from WAV files ripped from original CDs, and then encoded via AAC to 320kps files. Heck, even at 256kbps I was struggling. 128kbps can still be tough, but definitely a lot easier to tell the subtle differences. My high school CS teacher back in 2002 said he could easily tell the difference between mp3 and lossless, but back then, virtually all mp3s were poorly encoded, and the vast majority of them were low bitrates.
I've owned Asgard 2, and OG Mjolnir. The difference was minimal, but noticeable; both were pretty analytical. Now, I have a THX 789, and it is noticeably different from the former two. My Class D loudspeaker amp is very, very noticeably different sounding than the former three, and far superior sounding, may I add. Class D has had a low reputation due to their earlier implementations, but apparently they've improved by leaps and bounds. My Crown XLS 1502 makes my Sundara sound so musical, which is the complete opposite of what the THX 789 does. It's pretty much night and day. One is analytical, and flat/thin, and one is full-bodied, large-sounding, engaging, and obviously has enough power to melt the Sundara's diaphragms with ease. My first tube will be a hybrid, the Vali 2+, and it should be coming in a few days, so I'll know then whether it will be a big difference from my prior SS headphone amps.
I bought the Vali 2+ for a few reasons:
1. I want to dip my pinky toe into this tube world I've heard so much about.
2. I have a strong hunch that it will sound very similar to how my XLS 1502 sounds, based on many people's descriptions of what "tubey" entails. How they describe it is basically how I hear my 1502. When the Piety came around, I couldn't help but wonder if how people were describing its sound matches exactly how I've been hearing my 1502. I'm going to find out soon!
3. Even though the 1502 makes my EQ'd Sundara sing, the noise floor bugs me. It makes listening to anything low volume a battle with the hiss. At moderate and louder volumes, the hiss isn't audible, however.
4. I'm curious to know how replacing my passive preamp with the tube section of the Vali 2+ will change my system's sound. Again, will find out soon.