2. amps-preamps
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Benchmark AHB2 in Mono Block Configuration

Hi:

I've owned the Benchmark ABH2 Amp for a few years but am now considering one two alternative upgrade paths:

A New Amp or adding a second AHB2. If I purchase a new amp so far I like the Bryston 3BCubed which is a dual mono design with 200 watts into 8 ohms or possibly the 4BCubed at 300 watts. In either case this is more power than the single ABH2 at 100 watts into 8 ohms. However adding a second ABH2 increases the power per channel to 380 watts .

So much for raw power. What about overall sound quality? The Bryston 3BCubed got an excellent review on Absolute Sound as an amp that would require significantly more $$ to better. Another review I read easily preferred the Bryston 43Cubed (300 watts per channel) over the ABH2.

I'm in the process of completely upgrading my system after several years of the same components. I will shortly have:

An Aurender N20 Streamer into an MSB Discrete DAC with dual power supplies feeding the single ABH2 which drives my Harbeth C7es-XD speakers.

Everything will be new except the older ABH2. Hence the consideration of an amp upgrade.

Now Benchmark will tell you that adding a second ABH2 is only needed when the single amp clips. Other than that there is no sonic benefit to adding a second. I Ffnd that hard to believe. I would think having a second would offer improved soundstage, separation and possibly better performance from the speakers. So my question is:

Have any of you added a second ABH2 and if so what were the overall sonic benefits if any? Also any opinion or experience on the Brystons vs the Benchmark? Or any suggestions of a better upgrade path would be welcomed.

jfrmusic

Showing 9 responses by jfrmusic

jfrmusic OP
123 posts
 

@yyzsantabarbara 

Interesting experience with the ABH2. Although I don’t understand how the mono ABH2 would fair worse than a single driving lower ohm speakers since the power is significantly higher with the mono configuration 

@azlon 

I agree and also I will most likely sell my HPA4 as the volume control on the MSB will be sufficient. 

As to tube amps. Been there not going back. 
To all: Thanks for your thoughtful responses. I appreciate it. 

jfrmusic OP
123 posts
 

@lalitk 

I had dual REL T/5X subs but could not get them to integrate to my satisfaction with the Harbeths. The T Series RELs are really low end re enforcement rather than deep below 30 hz subs unless you move up to their bigger units. I liked the low end of the Harbeths which are -3db at 45 hz and my frequency analyzer shows output below 35hz. The RELs we’re just doubling up the natural low end of the Harbeths and it had a negative effect on soundstage and openness. 

jfrmusic OP
123 posts
 

@audphile1 

I will check out Coda and Kidman. And thanks for suggesting the Harbeth forum. 
 

@jeffreyw 

Yes the Benchmark doesn’t match the quality of the new front end. That’s why I’m looking for an alternative. 
 

@12many 

My dealer carries Bryston. He has all the equipment I purchased so I can demo the exact combination in the showroom or borrow the Bryston for a few days. He doesn’t carry Benchmark. I just got the Harbeths and really like them. So they’re staying. 

jfrmusic OP
123 posts
 

@audphile1 

sorry Coda and Luxman 

jfrmusic OP
123 posts
 

@jeffreyw 

I was conflicted about spending that much on the front end but I sounded so great. I remember from my old analog days not paying enough for the front end.  Once I committed to a Linn Turntable and Arm and Koetsu cartridge I was finally satisfied. I didn’t want to go through the endless upgrade path. Plus at my age time is a consideration. 

jfrmusic OP
123 posts
 

The difficulty for me concerning many desirable Amps is many are very large and very heavy. Not sure if can handle a 75-80 pound amp by myself. Getting it home and setting it up. The Brystons are reasonable in weight. And of course the Benchmark is a feather weight.

jfrmusic OP
123 posts
 

@timothy_m 

Thanks for the information and your experience with the AHB2. 

@yyzsantabarbara 

My AHB2 is Silver and 3 years old. I plan to try it with my new front end when they arrive. If I decide to sell I will let you know before listing it. I will als definitely be selling my Benchmark DAC3 and possibly the HPA4 as well. I want to try the HPA4 as a pre between the MSB and the amp first. 
 

@stereo5 

Thsnks I have watched that video. Very informative. 

jfrmusic OP
123 posts
 

Well I plan to compare it. 

jfrmusic OP
123 posts
 

Recent info from Benchmark Support   

No worries with the AHB2. In mono, it will drive down to 1Ohm. Into 6Ohms, the bridged AHB2 will output 480 watts.The input impedance whether stereo or mono is 50kOhms The amp will draw up to 8 amps. 
Also the specs state that distortion at all levels will be identical to Stereo mode and SNR will be 3db better in mono mode and that it will sound the same in either mode with the difference being available power in mono.   

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