The electrolytics that are problematic are not the coupling caps. They are both 600v 50 uf rated. I would speak first with Mike Sanders if or when there is an issue. The + leads on both fried manifesting in a howling sound from the amp. I performed the replacement of these caps until my friend who has regular contact with Mike Sanders performed the final fix which involved some minor mods to acommodate a beefier power supply and better caps.
I went through 5 different pre-amps before settling on a Bill Thalmann upgraded CJ PV9a which complements the QS amps in my set-up very nicely. I am using the Tung Sol KT 150 tubes which I prefer over the KT 88s, ymmv. A matter of trying both. I am unfamiliar with the KT 90 and KT 120 tubes in these amps.
Fsonicsmith you are spot on in recognizing the importance of the power and output transformer in tube amp designs. I am certain this is the primary reason why all QS amps are all so consistently excellent across the board. The mid monos are a great value at the price as is the 20 watt integrated. I have had zero problems other than the cap issue noted over the past 5 years. Yeah, Mike doesn't seem too keen or that it is necessary to "upgrade" but it must be noted, these products are still built to a price point and better performance can be gotten using better components. I'm with you on that deconney.
Enjoy your Zardozmike, you made a great choice!
