Hi Carl,

Thanks for your kind words. I decided it was time I got on the listserve, so here I am.

Your question regarding switching power supplies is a good one, which I addressed in my audioXpress review of the Benchmark AHB2:

As I note in the review, I spent several evenings comparing the AHB2 using one of my PS Audio Power Plant Premier regenerators, and plugging the amp directly into the wall. I was hard pressed to hear any difference. The AHB2 has a very sophisticated resonant-mode switching supply. Unlike conventional switching supplies, which generate a waveform loaded with harmonic content (i.e. noise), the resonant-mode types generate a waveform with very low harmonic content. This results in much lower noise.

Your question is timely, because I just bought an AHB2 for my home system, and plan to add a second one in a month or two (passive bi-amping, with one amp per channel). The two PS Audio regenerators that ran my mono power amps will go up on eBay soon. I’m keeping the third one, which powers my low-level equipment (Oppo digital player, Benchmark DAC and my own preamp).

I confess that I haven’t made the same comparison with my Benchmark DAC2 DX, which has a conventional switching supply.

Regarding hearing and age, I agree that hearing acuity may not have much to do with frequency response.


On 8/16/2016 7:47 AM, Carl Pultz wrote:
Interesting views, all. Thank you. And great to have input from Gary Galo, whose credibility for me is very high, as we both work in similar facets of audio. I haven't had a chance to try regeneration, but hope to eventually. For small monitoring systems, it is practical. Unfortunately not for larger facilities, as Corey points out.

Some years ago I was surprised by a utility crew, which came by to install a transformer right at my drop. I think there was only one or two serving my city block, and one of the guys said the new unit should help stabilize the line. Of course I played some music as soon as they were done. Sadly, I couldn't convince myself there was a difference. It is shared with three other houses. Maybe if my gear was more sensitive to the AC, it would have benefited more from the transformer, or from the newly bonded ground and power connections. I may also have less interference than a resident of Tokyo suffers.

We old-timers may be fully aware of this, but I always encourage audiophiles to have a dedicated circuit or two installed for their hifi. When I moved about 15 years ago, it was one of the first things I did, as my stereo was sounding like crap compared to what was going on in the old place. Living there in an older neighborhood, I was aware of the variation of sound quality day vs. night. That house was near by an antenna farm, so I had wired up shielded Romex with isolated grounds. Didn't go that far in the new place, but non-spliced runs on new breakers brought the magic back, with less variability than before. The service was 30 years old, so I tested and reinforced the ground straps. I couldn't measure voltage drop on the panel, but I wanted to be sure it wasn't contributing noise.

Some systems prefer to have all components on the same AC circuit. I've found that's often the case with tube gear, or products such as Naim systems, which are very concerned with common grounds. Remember turning the plugs each way to find the best orientation? Can't really do that now, and it probably isn't necessary with modern designs. When I was using a power-hungry Bryston amp, it definitely liked its own AC line. My current Benchmark components seem happier sharing. They use switching power supplies. I wonder if Gary looked into the effect of the regenerators while auditioning the DAC2/AHB2 system.

Anyway, I'm reminded of what I was told years ago when first getting serious about hifi: everything matters. If it matters to you. It can lead to madness. Or to joy.

We all can either lament or fear hearing loss. But, reading about the research behind the MQA coding system has turned me on (within my limited understanding) to the idea that high frequency perception isn't the only thing our sense depends on. Fortunately, other factors that are not so subject to aging are maybe more important. Note that our Japanese colleague spoke of dynamics, imaging, and clarity, which are not primarily dependent on bandwidth. My older brother, a professional brass player, has significant loss of sensitivity, an occupational hazard. We were together just last week and I made many adjustments to his hifi. He heard pretty much all of it, just at a volume level that I could hardly stand. But concert-like levels are non-negotiable for macho trombone players!