Developing critical listening skills


I’m not really an audiophile, but a long time music fan who values quality gear as a way to enjoy the music I love, so please forgive me if this seems naive. I’ve been experimenting with a lot of new gear lately, and with different resolution files, trying to see what differences I can detect. When evaluating hi-fi equipment, I have a good idea of the things to listen for, but find it very difficult quantify and compare differences. For instance, I just added new cables to my desktop system, and I think they sound better (wider soundstage, and more natural, less forced presentation), but I have a hard time identifying differences in a quantifiable way and really don’t know whether it is just an optimism bias. I can’t accurately remember how the sound was specifically different. I’ve always just listened to music on decent systems, but never tried to develop my critical evaluation skills: actually developing a systematic way to isolate, identify, contrast sonic differences. All the guidance I can find is very vague and general. Things like "spend a lit of time listening closely", or invest in the right hardware. I’ve already done both in spades. Are there some specific sort of reliable, audible tests that can be performed to build my skills? Any guides? I just purchased the Chesky Ultimate Demonstration Disc, and Sheffield Drive and A2TB Test Disc.

Similarly, trying to AB test files, and see if I can really hear a difference between 44.1/16 and a 256kbps file derived from the original, I honestly have a hard time. What should I be listening for? After a lot of listening to the same track, I think I’m starting to hear differences in the bass guitar, where the image a little smaller, and less resonant in the compressed file. Also, the cymbals are a little more sibilant, and with less depth and decay. But it is very subtile, and not too successful in an A/B test. Specifically what parameters should I be listening for (and how to I isolate & memorialize these characteristics repeatably) to start to build my listening?
svenerik
It's important to have two benchmarks, music that you know well played through a system you know well, and real live music.  When you audition a new piece, in theory you can then judge whether it then sounds better, worse, different or the same as the components you know, and the criterion for better should be it sounds more like what you hear as live music.
@svenerik Are you enjoying your music? Are you able to relax and let yourself 'be' in the moment during your listening sessions?
@david_ten Yes, listening and enjoying is something I've never had a problem with. I can say if something sounds good to me, or is somehow off or un-involving.  The skill I lack is being able to objectively evaluate & compare listening situations, and determine why something is off. Hence my desire to develop those skills.
@twoleftears i often hear of the idea of using live music as a benchmark. I can see how this would be of value when evaluating a live recording. The problem I have is that the studio recordings I listen to are typically not mixed to sound like like a live stage. The drum kit may be spread out in stereo, and while individual instruments can be pinpointed don't have the actual ambiance of a venue. So the recording never really sounded live to start with. And virtually all the live performances I see use sound reinforcement, so you are really hearing the house PA more than the instruments. Albeit the house PA at my favorite venue (The Baked Potato) is top notch.
The Harmon How to Listen is a useful site for learning how to . Also Audiocheck.net is great for testing a myriad of things on your equipment and your hearing capabilities and limits.  
@svenerik   First, kudos to you for being open to learning. Second, your questions are good ones and the responses posted are informative and will (hopefully) help guide you forward.

Adding to what has been shared, I suggest staying "tuned" / "alert" to your emotional connection and engagement to the music as a significant metric. We tend to deconstruct (emphasize deconstruction) in this hobby...therefore, the reminder to consider the whole.

I also recommend broad strokes first. One doesn't need intimate familiarity with recordings to assess elements such as pitch, tone, timbre, timing, etc. Use your own definitions (understanding) of these as a starting point.

Good luck. And make it fun.