My system does double duty (7.1 surround sound for movies and 2.1 stereo). The details are listed in my signature. Over the 15 years or so, two purchase stand out as being disproportionately impactful in terms of the improvement vs. the expense.
One, I purchased what I consider to be my first piece(s) of truly “Hi-Fi” gear: Anthony Gallo Acoustics Reference 3.1 speakers (which I still run with today). It’s a cliche but these speakers punched well about their price point when they were new and, in my opinion, still compete with many of the more expensive offerings in the market today. MSRP back in the day was about $3,000 a pair (U.S.). These speakers and their successors have been reviewed as much or more than any kit I have observed during my time in this hobby. For, me their greatest attributes are that they are arguably a true full-range speaker and, when placed properly, are convincingly holographic and completely “invisible”. For $3,000 at full MSRP, when new! They are a stone-cold bargain on the used market today. One of the many reviews is linked below, which describes some of their strengths.
The second big bang for the buck experience for me was the addition of a used Anthem AVM 50v, replacing my Anthem AVM 20. The AVM 50v comes with Anthem’s positively reviewed Anthem Room Correction (ARC) software. Have you ever had the experience of tweaking your system or adding a component such that the improvement was so startlingly good that removing the tweak or piece of kit from the mix made you not like the sound of the system that you thought you were satisfied with before you made the change? (A rhetorical question for many in this forum, I’ll bet.) Calibrating the 2.1 and 7.1 set ups using ARC was revelatory in my room/system. Individual aural clues, instruments, voices, etc. are clearer/sharper and low frequency sounds are less fuzzy/tighter – the presentation is just cleaner (maybe Paul McGowan would say, more transparent to the source?). Every once in a while, after I make some other change (like adding the PSA DS DAC to my system, treating the first reflection points in the room or playing with speaker placement), I’ll turn off the ARC DSP adjustments to check on the “unprocessed” sound of the room. So far, I have always had to flip the DSP switch back on in hurry. Maybe someday my components and room will reach the point where ARC will yield nothing but an immaterial, incremental difference in the sound that I can live without, but not today. The AVM 50v retailed for about $5,5000, when first introduced to the market. I picked one up on Audiogon for about $1,000 bucks a couple of years ago. I have also linked to a two-part Secrets of Home Theater and High Fidelity ARC review below.
I would appreciate it if others would share some specifics about their experience with big improvements for, relatively, little investment. For me, it is not about the cost, but the value of the purchase that I find satisfying. “Big Bang for the Buck”, if you will, is what draws me to PS Audio products, as well.