heres my situation. I have a Carvin legacy 100 tube head, that acted real funny (and still is) this past weekend. At higher volumes (3 or higher) this thing is LOUD! i mean reall loud! so let me expain what im experiencing...... i turned it on ( guitar is pluged stright into the amp, no pedals, nothing in the effects loop), and as i turned up the volume, past 3 or 4, the volume didnt increse all that much, the only thing that happened was a "choking' sound and more increased clipping/un-wanted distortion. The higher i turned up the volume...the more it started to "choke". At volume 5, usually this thing is rattleing windows, and rumbling walls.......but i could hold a normal conversation with my friends, and we were talking louder than the amp! and it was on volume 5! All it did was just "fart' out, 'choke" and clip like crazy the more i turned up the volume. and this happens to both the clean and dirty channel. so i changed all the cables (both guitar and speaker cables), nothing improved. i switched out the v1,V2, and V3 preamp tubes.......nothing changed. i looked inside, and the power tubes appeard to look fine....no red glow, and no flickering. BUT i did notice a very small amount of black burnt marks (very small) on the inside of the glass of my V7 and V8 power tubes near the upper portion of the plates. But they still appeard/looked to react as normal. what could be causing this? maybe the V5 phase inverter needs replaceing/ or maybe the power tubes are in need of replaceing? or is it something totaly differnt?