This sound system is for a virtual organ project that has been evolving over time, so the purpose is to get the best sound I can afford out of my computer and into the room. The instrument's primary purpose is for playing in church. Our current congregation is tiny (15-20 is a good week) and our worship space is about the size of a large living room, so power requirements are modest. I started with bringing along my home stereo receiver and a pair of all-original vintage speakers after the "house" system was first wildly unreliable for me and then quit entirely. This use exacerbated the hiss I can normally ignore in that (also quite ancient) receiver, plus I really wanted it back at home for listening to records, so clearly change was needed and I started piecing together something better.
Here's the gear I have so far, downstream of the computer:
ART USB-DI audio interface
Behringer X802 mixer
DBX 223 crossover
ART SLA-4 four channel amplifier
2x Klipsch KG.5 bookshelf speakers
1x REL HT1205 sub, dead plate amp replaced with plywood and powered from channels 1/2 of the SLA-4
Component selection has been based on what I imagine are the usual criteria: Known needs at the time, price, reports of satisfactory performance, and opportunity/availability. The sub, for example, I got for about $150 shipped vs. about $900 for a new one. When I initially ordered the two ART components new, I didn't know that a DI box is specifically for outputting a very low level signal, but it was a good price, does only one thing, and I think it sounds better than other interfaces I've tried, so for now it's staying. The selection of the X802 was incredibly scientific , the the result of 1) discovering I needed a preamp, 2) a guy telling me that model's decent and another guy backing him up from experience, and 3) discovering my local secondhand music shop had one for $45. The fronts should be upgraded eventually, but were an opportunistic buy that I was thinking of using at home, but when I heard how decent they sound, combined with their ability to hide away in the corners, they joined my church system, replacing a pair of all-original KLH 33s that I really like having in my basement. The SLA-4, while admittedly on the cheap end of pro amps, was still spendier than I preferred, but buying new seemed a good way to avoid reliability problems, and I had the idea of transitioning to 4-channel sound someday and thought it could grow with me.