Hi mcandmar,
Sorry that I didn't notice this before today, but I just wanted to give a quick message. I'm glad to hear you went with the (non-assembled version of) the same attenuator I went with. A couple things stood out to me when I installed this. First, the detail was noticeably improved. And second, on closer listening, the channel balance is better throughout the volume range. I'm sure, if you don't have it installed yet, you'll be very happy with it. I would not be surprised if a nice (expensive) attenuator was compared, that this would show some deficiencies, but for the price, I think it's hard to beat. Maybe one day I'll be able to do a no-holds-barred amp, but for now, I'm happy to be able to use mid-level upgrades to gauge the importance of each component in the design.
Also, as you say, I'd definitely suggest getting the assembled version. It's just not worth my time to solder in 90 resistors to save $10 or so.
Best of luck!