I play bass with a ska band called Driver Friendly. The band is pretty loud, what with the hornline and everything. Anyways, I've got a Gallien-Kruger 400RB combo - the one with 275 watts through a 15" speaker. My problem is, when I turn it up loud enough to gig with the band, it gets a kind of gross splatty sound. I'm not turning it up all the way, I have the master and the volume controls both at about 5, and I get these gross splatty type sounds. When the amp is turned down lower, it sounds great, but once I turne it up, pretty gross. This really can't go on since we gig almost every weekend, and it really gets on my nerves. My question is, is this a problem with my amp not having enough wattage, or do I just need maybe another cab to combine with the 15". I'm really a guitarist, so bass amps can confuse and scare me... Any help is really greatly appreciated. I have about $1000 that I could spend on a rig, but I really don't want to spend that much... especially if all I need is maybe another cabinet. One more thought I had on this - I have a Yamaha 660 powered mixer that the band doesn't use. It has two 300 watt amps. Would it sound okay if I were to buy a big subwoofer (I saw a yamaha 18" sub in the Musicians Friend catalog) and use the XLR outputs (or maybe the line outputs) on my GK to send it through the PA and from there through the sub? Then maybe I could use my actual amp as a moniter and use the PA to power the sound I send into the club. I asked some people about this, but they said that it probably wouldn't sound very good. Anyways, any help is greatly appreciated. If you have suggestions as to what I should do or what kind of gear I should get to fix my problem... I will be forever indebted. Thank you very much!