Hey all,
I just inserted the 7581As and fired up some Steely Dan. I know it's hard to A/B audio, especially when an entire day has passed between listening this morning to the stock Chinese tubes and right now listening to the 7581As. But, I can tell you that after only 10 minutes, the difference is huge. It's like the towel has been lifted off my speakers! Much cleaner highs, unmuddied bass, and a much more open and airy sound stage. I only have the stocks to compare these to, but I'm really, really happy with the difference! Now to play them for 30 or 40 hours!