Hi Peter
Initially I would be tempted to agree with Dan but there shouldn't be an impedance mismatch with the Berning/Pro-ac's. It must be elsewhere in your system or set-up. There is another proac/Berning user (Ian where are you?) that loves this combo. Obviously (at least to me) there is something wrong here beyond what you expected. There should be NO tube glare unless there is an interface problem with wire, certainly not from the amp unless you have a bad tube(s) which is possible, but somehow I doubt it, Berning is too meticulous to send out a new product with such a defect. Upgrading tubes will enhance performance but that is not the answer for tube glare with the zh270, break-in possibly.
An emphasis on the midrange is something more puzzling and I have no answer off the top of my head because I don't hear this in my system and never have nor have I heard it with other speakers and the zh270. I would agree that the bass through the Berning won't offer the slam of other ss amps but it should't be a problem, to the contrary. Bass should balance well with the mids and highs. This amp is all about superb tonal balance along with that clarity. You don't mention high frequency performance at all which with the right speakers and wire should be top shelf. So now all that is left is to troubleshoot.
Have you tried the 3 feedback settings. Do you note any changes between them.
What is the amp sitting on, how close to the digital source. The amp uses ultra high frequency so there could be a possible problem with the location of the amp that may be contributing to what you are hearing.
As Dan asked, are you running directly from your digital source to the amp or do you use a pre.
Certainly the MIT's in general are forgiving cables and shouldn't present a problem at all. The fact that you have tried so many different cable configurations leads me to believe that this isn't the foundation of the problem either but still...it wouldn't hurt to try something else, maybe Cardas. I am using Luminous Tech Syn Sig cables with superb results.
Lastly it could be a break-in of the amp. I wouldn't completely eliminate this. I have heard it first hand and it can never be ruled out. The bottom line is the Berning with the pro-acs should be singing in your system and you shouldn't be hearing any of what you are describing. Please keep us updated. I am confident you will find the problem so hang in there.
Initially I would be tempted to agree with Dan but there shouldn't be an impedance mismatch with the Berning/Pro-ac's. It must be elsewhere in your system or set-up. There is another proac/Berning user (Ian where are you?) that loves this combo. Obviously (at least to me) there is something wrong here beyond what you expected. There should be NO tube glare unless there is an interface problem with wire, certainly not from the amp unless you have a bad tube(s) which is possible, but somehow I doubt it, Berning is too meticulous to send out a new product with such a defect. Upgrading tubes will enhance performance but that is not the answer for tube glare with the zh270, break-in possibly.
An emphasis on the midrange is something more puzzling and I have no answer off the top of my head because I don't hear this in my system and never have nor have I heard it with other speakers and the zh270. I would agree that the bass through the Berning won't offer the slam of other ss amps but it should't be a problem, to the contrary. Bass should balance well with the mids and highs. This amp is all about superb tonal balance along with that clarity. You don't mention high frequency performance at all which with the right speakers and wire should be top shelf. So now all that is left is to troubleshoot.
Have you tried the 3 feedback settings. Do you note any changes between them.
What is the amp sitting on, how close to the digital source. The amp uses ultra high frequency so there could be a possible problem with the location of the amp that may be contributing to what you are hearing.
As Dan asked, are you running directly from your digital source to the amp or do you use a pre.
Certainly the MIT's in general are forgiving cables and shouldn't present a problem at all. The fact that you have tried so many different cable configurations leads me to believe that this isn't the foundation of the problem either but still...it wouldn't hurt to try something else, maybe Cardas. I am using Luminous Tech Syn Sig cables with superb results.
Lastly it could be a break-in of the amp. I wouldn't completely eliminate this. I have heard it first hand and it can never be ruled out. The bottom line is the Berning with the pro-acs should be singing in your system and you shouldn't be hearing any of what you are describing. Please keep us updated. I am confident you will find the problem so hang in there.