Help please with AC line voltage problems......

I am really lost on this one. I recently had my ARC VT200 go ballistic (a tube went and put on quite a fireworks show). When I took it to my tech he said it was probably becouse our city power is so bad (sagging very much in the day and spiking at night). This voltage corruption is in turn multiplied in the driver tubes of my amp (BAD), and can cause some serious problems.

I currently run my amp straight into a dedicated 20amp line. I have benn thinking of a power conditioner/surge suppressor/voltage regulator but really don't know what to get. I don't want to limit the current on my amp (which draws a lot). I have heard that products like those from PS audio do good and bad things to the sound, and use a lot of power themselves.

My tech suggested an autoformer, does anyone use such a device?

I really need help here......... I dont want this happening again....... There are so many claims to great sound out there, but who's approach is right?

Does anyone use the Furman units (I see them quite often in pro-sound applications but not in the home)? Also I am wondering about the Shunyata Hydra (new model)

Thanks in advance