Tube rolling and SAC Glowmaster KT88?

Thanks for taking the time Hiker to post your thoughts. I was really led to the Glowmaster by a desire to try valves after 10 years or so of solid state. I picked up an Art Audio Concerto power amp earlier in the year to experiment and whilst it was good it didn't quite have the grunt to drive my speakers like my Gamut D200. I emailed George at NorthCreek and he recommended a well designed tube amp of around 70 watts should be ideal. So I poked around a few forums and came across someone who had replaced a D200 with the SAC KT88 and was delighted with it. I checked out the Hifi World review, which seems to be about the only one out there and then bought it without first hearing it...and don't regret it for a second.
I was considering the Winged C myself and I have also heard good things about the Electro Harmonix KT88 generally but your positive experience has probably just tipped the balance in favour of the Svetlanas.
I also did some research into swapping out the 6N1P tubes but like you I found that all new production units are identical. Out of interest have you tried rolling in some NOS 6N1P valves?

Well Hiker, I have taken the plunge and ordered a matched quad of winged Cs so thanks for the benefit of your experience. I'll report back in due course and let you know how they behaved in my particular set up. If anyone else has contributions to make to this thread then please don't consider it closed. This Glowmaster amp is a 'keeper' so I'll be interested in any tweaks, which you feel wring the most out of your unit. I have replaced the stock power cable with a Zu Bok which made a significant improvement and I have ordered some LSU No Spikes (I believe they are called "Spike Sound Will" on the other side of the pond) to evaluate for isolation purposes as the amp is too heavy for both my SAP Relaxa and Seismic Sink.
Of course, any alternative tube combinations i'd be fascinated to hear about...

I received my Winged Cs yesterday and plugged them in only to find that despite ordering a matched quad, one was severely off and I was unable to bias it whilst another was just alarmingly off, two were spot on. I suppose I would never have known if the Glowmaster didn't have the LCD display!
Consequently they all went back and I probably won't be able to play until next week now when the replacements arrive (fingers are crossed for a Saturday delivery but that really would be the triumph of hope over experience!).
Thanks for the tip about Jacmusic.com Hiker, I'll check out what they're offering whilst I'm in tube limbo.

I have put a few hours on the "C"s now and I'd have to agree with you Hiker, they have made a great amp even better. Better right across the frequency range and a soundstage you could almost step into. Thanks for your advice, it was much appreciated.