To Diego Estan and Doug Schneider,
Thank you for doing such a thorough and in-depth review of the Anthem STR preamplifier and its feature set.
The STR preamp has been on my radar for over a year because my listening room has open left and right front corners (effectively no front corners), and, as a result, the room provides little bass re-enforcement for any pair of loudspeakers. I find it necessary to use a subwoofer to help generate adequate bass, even when using fairly potent tower speakers such as the Bryston Middle Ts. I am now considering increasing from one subwoofer to using two for even better bass response. The STR preamp’s comprehensive feature set with bass management and support for dual subwoofers is very appealing.
I am quite intrigued by the STR preamp and its outstanding feature set, but at this stage I am looking for advice and opinions on the STR preamp related just to system matching with my existing Simaudio Moon 400M monoblock amplifiers. I am also curious how the STR preamp might compare sonically with my much more expensive, purely analog Simaudio Moon P-7 preamplifier (discontinued in 2013). I don’t have an opportunity to try or borrow an STR preamp at this time, so below are two questions (items 1 and 2):
1) Gain matching: my Simaudio Moon 400M monoblock amplifiers have a higher-than-typical gain specification of 36dB (most power amps are rated about 29dB). Might the STR preamp’s analog gain of 18.6dB (as measured by Diego for the balanced outputs) be a bit too high to be a good match for my 36dB Moon monoblocks?
Or worded differently, might the combined gains (18.6dB and 36dB) of the STR preamp and my Moon 400M monoblocks result in very little useable adjustment range on the volume control before it becomes far too loud? To compare, the Moon P-7 fully balanced preamplifier that I am using with these monoblocks has a gain specification of 9dB, and the new Moon Neo 390 preamp-DAC-streamer from the same Simaudio product line as the 400M monoblock has a gain specification of 10dB for the balanced outputs. I realize that the STR preamp is designed to pair with the matching Anthem STR power amplifier. Has Anthem indicated what sort of volume control implementation is being used (potentiometer, chip, R2R ladder, etc.)?
2) Analog performance: Diego’s review of the STR preamp indicates that it was indistinguishable from his well-regarded McIntosh preamp, so obviously the Anthem STR’s analog performance is really good.
However, any “guestimate” how the STR preamp may sonically compare to my older but almost-twice-as-expensive Moon P-7 fully balanced preamplifier? (My Moon P-7 preamp was purchased secondhand, but it was very well regarded as an analog preamplifier when still current in 2013.) Doug separately reviewed the Moon P-7 preamp and 400M monoblocks several years ago. This is why I have also included Doug in this conversation.
Thanks for the kudos and reading my review. I must admit, the STR consumed me as a reviewer for a few months. There are so many features and so much versatility that my time with it yielded not only the review, but a few accompanying articles as well.
My short answer is that if you are going to be using dual subs, the STR is a good turnkey solution for you, offering both bass management and room EQ.
Now, to specifically answer both of your questions:
First, the 18.6 dB of gain I measured was across the hot and cold pins of the balanced output. While there is no standard way of doing this, most manufacturers would report gain from single-ended input to singled-ended output. It’s therefore perhaps fairer to say the STR has 12.6dB of gain in analog mode. For example, my McIntosh C47 is rated at 15dB of gain, but if I measure across the balanced output, I measure 21dB.
I wouldn’t worry about having too much gain and not enough volume adjustment. The STR provides 206 volume steps, in 0.5dB increments. Due to the extra gain, at normal volume levels, you will likely hear a bit more noise/hiss with your ear near the tweeter compared to your Moon preamp, not only because of the gain difference, but because Simaudio makes very, very quiet electronics. I’m willing to bet, however, that with your average-sensitivity speakers, at normal volume settings, you will hear absolutely no noise from your seated position. While I can’t tell you precisely what chip Anthem uses for its volume control (they have not given me permission to do so), I can tell you that it’s a well-regarded R2R-type integrated circuit. Attenuation is digitally controlled, but performed in the analog domain. Also consider that the STR offers up to +/-20dB of gain trim, in 0.5dB increments, on any input, should you choose to use it.
Finally, even if there were subtle differences in sound between both preamps, these would absolutely pale compared to the sonic benefits that the STR would bring in terms of bass management and EQ. Of course, you can also opt to keep your Moon preamp and explore external solutions for bass management and room EQ, which is what I did before I knew the STR existed. But you may encounter a steep learning curve with that approach, so it depends if you’re into doing the required homework/research.
I hope that helps. . . . Diego Estan
I’m not sure if you’re aware, I wrote about the STR preamplifier on SoundStage! Hi-Fi this month. As a result of my experiences with the STR, I agree with Diego that with what you want to do with speakers and subwoofers, the STR is the ideal way to go as a turnkey solution. I also can’t add much more to what he already said, except this: I am more wary than he is of the gain issue that you pointed out, not for volume control, but for potential for increased noise. I’ve had noise issues with some preamplifiers and amplifiers I’ve reviewed over the years, so it’s something that jumps to mind when someone talks about matching a certain preamplifier to an amplifier that’s out of the norm.
We measured the Simaudio Moon 400M when I reviewed it, which revealed the very high gain you mentioned -- 36.2dB on both the single-ended and balanced inputs. That’s a lot more gain than with most amps, which could result in excessive noise from a high-gain preamplifier. Not surprisingly, Simaudio’s preamps have lower gain. To know if it’ll be an issue with the STR, though, you’re really going to have to connect the STR to your 400Ms in order to find out. I know you said you couldn’t right now, which I understand, but, to me, that’s the prudent thing to do, just to see if the noise is an issue and you’re making the best choice. After all, if noise isn’t an issue, and you like everything else about the STR, including its second-to-none feature set, that should go a long way toward making the decision for you with your current system goals. . . . Doug Schneider