I recently bought a used Sunn 300t (ebay). Unpacked it and all seems to be in excellent shape (cosmetically speaking). Before powering it up, after it's long trip, I went over it all making sure the tubes were well set in as well. I pulled the fuses out and noticed that the AC fuse was blown to hell... charred, fried, scrambled - all that! This immediately drew red flags however I have read enough about the fuses blowing on these series of amps for various reasons. Before proceeding, I ordered new fuses, including the 3 fuses at the pairs of power valves. Now the concern: The AC fuse that blew was rated at twice Volt rate. The blown fuse was a 10A / 250V fuse when the specs call for a 10A / 125V fuse. So it blew a fuse with a higher voltage rate than required!! What else could hva possible blown. Also, two of the three valve fuses were 500mA when the specs call for 100mA. These were all OK with the exception of the actual 100mA fuse appearing to have a little dark browning in the center of the glass (connector within still in tact though). Now that I have replaced the fuses, it will power into standby, no problem. The only problem is that of all of the power valves, the first one in the series doesn't light up or even warmup in the slightest when in standby. Figuring, I was going to be returning it anyway, I tried to connect to a cab and take it out of standby to see what may happen. When I take it out of standby, the power valved begin to glow and the amp is giving off a loud low freq. hum. One of the power valves (in the last pair) will continue to glow brighter and brighter as if it's about to explode. Soon into the out-of-controll valve glowing, I shut it off. The tubes look very old and I can assume one may already be dead (unless it's an issue with the socket or even a more internal flaw). I have committed to going with a high watt, all tube head and would really like to get this one going. I guess the question would be, based off of what you're hearing or have maybe even experienced yourself, I'm considering all possibilities for flaw and to what degree of damage or measure of doctoring will it take to get it back to peachy? If I am going to have to buy a new set of power valves ($200-300) and then even take to the local pro amp tech... I may be looking at the price of a new Ampeg SVT-CL Heritage by the time I'm done. I went with the Sunn because it was a cheaper alternative (assuming it'd work) and I'm pretty partial to Sunn / Fender amps. One thing to note, when I switch out of standby and the lone tube begins to glow to the degree of becoming the next closest star to our planet - the bias led indicators are all glowing green, as if the amp thinks they're all within proper bias range and just fine. If this (loud hum, one tube glowing excessively, etc.) could simply be the result of a shotty set of valve tubes, I don't mind replacing them with a new set. If it is more likely or from an amp tech's perspective, seems it'll require more internal work (like capacitors or worst), I don't know if it's worth the gamble of trying to get it going? If there are any amp tech's that can chime in on the issue (from an instinctual or professional point of view) or those who own these an may have experienced something similar, I'd be curious to hear alls opinions. I'd like to think it has hope, but not to drop $5-600 into it to find the cost would no longer make it a reasonable.deal. Any and all input and theories welcomed and appreciated.... Thx!