I've been using good Sony and Audio Technica headphones for practicing, but they become a bit uncomfortable after wearing for a while. So I've been playing through my computer speakers which is an old Altec Lansing ACS45 Powercube system (satellites/subwoofer) and it sounds excellent, much like a real piano with great balance and tonal representation of lows, mids and highs. However, not really meant for this "live" application, they're underpowered and with the volume at around the same level as a Steinway D including dynamics (yes, I'm very familiar with them), the small satellite speakers distort and rattle. Yes, I can turn them down but prefer to rehearse at familiar volume to experience the approximate dynamics I'm accustomed to on a real piano.
I just tried a pair of Numark NPM5s and had plenty of power but sounded terrible....very mid rangy with poor highs. Sounded like I was playing through a tunnel and there's no EQ except Pianissimo's EQ which didn't help much.
I don't want to get crazy with all sorts of sound equipment just for practicing, so if anyone has suggestions for a decent powered speaker system direct from the computer's sound card, please let me know. Judging from my experience with the Numarks which have 5" woofers in each cabinet and didn't produce as good of bass as the Altec Lansing subwoofer system, I'm thinking a more powerful subwoofer system might be the way to go. ???
UPDATE: I've tried a few different speakers including 200w Klipsch and nothing has been able to faithfully produce a full range piano sound as well as the Altec system, so will stick with that for now. I'm finding myself using headphones more, so plan to purchase better, more comfortable phones.