I just bought an Avatar 2x10 and a 1x15, both at 8 ohms and I also want to upgrade my amp. I am short on cash and probably shouldn't be doing this, but I am proceeding despite my financial situation. I play in a fairly loud classic rock band ATM, and I need good clean power that will allow me to cut through 2 guitars, supply a strong foundation and play solos. This is my dilemma: I have a source for getting a virtually new QSC PLX1602 for a bit over $500. I also can get an Ampeg B-5R for about $550. The advantages of the QSC are: 1. Power 2. 2 rack space 3. 21 lbs. But I still need to buy a preamp. I figure I can get a used pre on ebay for $200 or less if I don't go too fancy, making my total outlay a bit over $700 (ouch), and my spacing needs at 3 rack spaces and about 30 lbs. The Ampeg: 1. Has a cool octaver built in 2. 2 rack space 3. 20+ lbs. But the power (at 4 ohms total) is either 340 or 350, depending on which Ampeg ad you read. Ampeg has a problem with consistency in their ads as they list this amp as 32 lbs in one place and 20 lbs in another as well. I like the Ampeg solid state sound, but I don't know if this unit will really have sufficient power. However, the B4R would probably run me more like $900, but it would also have a biamp feature. I currently use a biamped rig and I like biamping, so this also favors the QSC option as many pres have a crossover, although this also rules out a number of pres as well. I also probably will have to go with an old Yamaha PB1 or perhaps an ADA MB1 to keep the pre under $200 and still have biamping capability (and I wouldn't get the built in octaver, but I do have one anyway). I like the idea of getting down to just 2 rack spaces and low weight for the whole shebang, but the relatively low power, lack of biamp capability, and strange distortion channel on the Ampeg are concerns. Any advice?