When you connect the BA via the XLR inputs, does the fixed RCA "Loop" output work?
Yes I think it does. I once connected with the RCA loop (using BA as preamplifier) to the balanced
beta 22 and it worked very well. I connected the XLR inputs from the Weiss DAC202 to the BA.
You don't have to turn on the BA to use the beta 22.
I was wondering if anyone took any upgrades for their BA?
If you mean the PX25 modification and the BL63 modification : yes I did. If you use the NOS PX25
you should go for it. The modification will help the performance of the PX25 while the WE300B may sound
a little bit dry but still great sounding but the PX25 and equivalents will shine . I have used the Osram PX25,
Mazda PP5/400 , Radiotechnique F410+TF-B10, Tesla RD27AS with great results. In fact I like it more than the 300B .
For the BL63 modification, not so much improvement as I use the BA to drive the LCD3 which I think 6SL7
is a better driver (BL63 has less gain than the ordinary 6SN7's so much less than the 6SL7's). May be the BL63
will pair better with the more sensitive headphone like the Grado's and R10 but I have no chance to try that.