I've been using my GC as main amp for almost a year now and I have the exact same experience with my GC as you. In fact, my system's very close to yours. Grounded-grid tube pre-amp and GC powering a 2-way high-eff speaker (BR bottom, compression horn top).I got caught up with all the excitment of T-amps and was looking forward to experimenting and building an inexpensive high-performer with this technology. Unfortunately, the costs seem to add up quickly. Considering there's no substantial improvement, I'll stick with GC's for now.