Hey, I play electronics (Samplers, Effects Pedals, and Synths) with a guitarist and another keyboardist/samplist and I have been looking for a PA (some speakers and possibly a sub) that would fit our needs. We're playing smaller venues and art gallery places. I've looked at buying guides and other threads but a lot of them seemed to be focused more on larger venues, and as good as the QSC K Series looks to me, I think it's too powerful and too expensive for us. Also, a lot of the speakers I was looking at didn't have many reviews or seemed crappy.
So, I guess I'd like something midrange in price and power with a sub bass. I think something with a full range of frequencies and some emphasis on low frequencies is what we want. All active speakers would be nice (from what I've read).
Here's a list of equipment that I'm using if it's helpful:
Roland SP-555 Sampler (Covers much of the low frequency range)
Korg Microkorg Synthesizer
Yamaha MG102C 10 Input Stereo Mixer
The K-series is a good option. So is the JBL PRX series. Which K-series model are you looking at? For the venues you describe, the K10's would actually sound great- plenty of power, and smaller and cheaper than the 12's. You can always add the sub later as funds allow.
Below that, I'd consider buying used before I'd buy something lesser. You could get into used Mackie SRM-450's or EV SXa 100's for less money than new K's, and they'd be better than any of the cheaper new options. I think it makes sense and is actually cheaper to buy good gear and buy once, rather than buy cheap stuff and buy twice.
The EV ZXA1-90 or the ELX112P active with one sub would be good. The QSC are great and would not be to powerful at all. You can set your gain structure up where you are not sending to much sigal and it will sound fabuluos at lower levels. The trouble with 8 or ten inch speakers is that they have a wider coverage pattern than the 12 inch. A 8 inch woofer can have as wide as 120 degree coverage which unless your in a very wide setting could cause canellation problems. The 10 inch is 100 degree and the 12 is 90 degree. A 15 inch will actually be a narrow as 75 to 60 degress depending on the box. I think the 12 has the best sound with a sub for lows and can get low enough without sub for sum uses.
If you send a -4 to 0 (unity) on loudest for gigs where you do not need as much SPL will make for a super clear sound and you will have tons of head room when you need it. Set the speaker gain lower and you will have Less trouble with feed back.
Kustom makes cheap little pw50s, which i'm pretty sure are 100W self-powered speakers. They go for $100 so you could buy 4 if your worried about playing a somewhat larger venue than an art gallery. But for what you stated 2 should suffice. Kustom also makes a subwoofer... I think it's the pa112s. It goes hand-in-hand with the pw50's and sells for $200.