I finished the Smash over the weekend.
The build took about 6 weeks of off and on work with a couple of week long intervals with no building. I took it slow as per previous advice. I am novice with a couple of previous kits under my belt.
Problems: 1) I had never used a self tapping screw and holding the bracket properly took some figuring, 2) I failed to follow "attach" vs "attach and solder" a couple of times and had to use solder wick and a desoldering pump, 3) resistance checks were fine but upon initial plugin one of the LED's did not light up and some of the voltages were off on that side. I inspected wiring and reflowed a couple of joints in the area of incorrect voltages and tried again I noticed with the top plate bottom side up the the 4P1L tubes were loose and one fell out. I was putting it back in and I noticed that when it was held a certain way the LED lit up. I pushed both 4P1L's a little further into the sockets and they felt more secure. Now both LED's were fine and voltages correct.
Sound: With my little Pass DIY monos and some old KG4s from ebay (Crites diapragm and crossover kits) the sound of CDs and Spotify through Meridian Direct DAC is amazing. The system is clearly better with the preamp. Microphonics were helped by attaching some foam weather stripping to the case bottom and to the rabbeted edge. Feedback was helped by not having the speakers on the same rack.
This is a great preamp that is fun to build and has a fantastic sound. I'll eventually get around to the Smashup but plan to enjoy the current set up for awhile.