Someone asked me these questions via PM, and I thought I would respond here in case anyone else would be interested:
Does the BA sufficiently drive the HE-5? Or is the EF-5 more appropriate and pairs well?
The BA can drive the HE-5 and LCD-2 with no issues at all in terms of power. However, the EF-5 does have more power.
I feel that the HE-5 midrange and vocals sound distant and not forward/intimate enough, which of the BA or EF-5 do you think is warmer-sounding and would bring forward the midrange and vocals?
The BA with 45 tubes. With 2a3 tubes, the soundstage is wider, but there is less 3-dimensionality (the z-axis is flatter). With 45's the soundstage is narrower, but more 3-dimensional, there's more body, intimacy, and the musical performance sounds more natural to me. The 2a3's do have a little bit more PRAT\bass attack than the 45's. But both the 2a3 and 45 on the BA sound much better than the EF-5. (I use an Amerprex Bugle Boy in the EF-5.) And yes, detail and every other aspect of the sound and music is better on the BA than the EF-5.
Price and detail refinement aside, which of the BA or EF-5 is more neutral and which falls into classic lush tubey sound? Do you feel that the BA provides wider and deeper soundstage?
I'm not sure I can tell you which is more neutral, as neutral seems to have multiple definitions. According to the Head-Fi definition, the EF-5 is more neutral because it sounds very flat and boring in comparison to the BA. However, according to my definition, the BA is more neutral because it sounds more natural and more like what I would hear from a live performance. It's just more real sounding. Given that though, the BA is more lush sounding (in a very good way - not slow, muddy, rolled off, or anything like that), but I attribute that to different sonic characteristics than just frequency response. No matter how I EQ the EF-5, I could never get it to sound like the BA.
I'm aware that it's not fair price and balanced-wise, but I would like to know whether the more expensive BA would do justice to my HE-5.
It would improve the HE-5 for sure. But to be honest, I'm not impressed by the HE-5 (I've never heard the LE version or the HE-6.) If the HE-5 is your best headphone, I would much rather sell that and get a different headphone before buying the BA. But the BA is a great amp once you have great headphones to appreciate it. As a simple comparison, I would compare the HE-5 to the LCD-2, as the EF-5 to the BA. The HE-5 and EF-5 are flat, boring, unremarkable sounding componants compared to the more exciting and interesting sounding LCD-2 rev. 2 and Balancing Act.