Its a shame I no longer have access to an oscilloscope.
I think you're right though, the price of some DACs are scary high and they must adhere to the rule of diminishing returns as with everything else in our hobby :)
Back on subject.
My results for the "Potato Masher" are in.
For its price its a great tube however even with my HD650s I find it a touch bright and fatiguing but as a backup tube its a good one to have around. The largest drawback is that it is ugly as all hell and makes my WA6 look horrible! All of my listening was done with a set of GM 6EM7s and will test it again next week with a set of 6SN7s that I have that are not as bright to see if it sounds a little nicer.
Also, just received a great looking Sel Lorenz 1971 GZ32 to test out when I get home. Will let you know how it goes.
oooh the 5R4WGA thing you mentioned earlier? yeah doesn't look very good lol.