In year 2000, I had cutom built an Amp from Cary Audio , with all possible upgrades and features , as well as features like , dual speed cooling fan , soft start cuircut , volume pot , headphones jack , triode ultrlinear switch, etc . Last year I sent it for service to Cary , and had many parts replaced and upgraded. The amp has been giving me great service all these years . I believe it gives sound for which I would otherwise need to spend many times more .