Back to answering Nr9's questions ...
"I have heard that the new units are supplied with better cabling and capacitor. Do you know anything about this?"
As far as recent model Berning ZH270 amplifiers being supplied with the upgraded silver wire and upgraded capacitors, I believe that is a premium option that needs to be requested when ordering the amplifier. My understanding is that most buyers have lately requested these options when ordering, based on the feedback here on Audiogon. I purchased mine used here on Audiogon with the silver wire and capacitor upgrades already installed plus the cryo-treated 6JN6 output tubes. I suggest contacting Allan Bhagan for a more definitive answer.
"I’m looking forward to receive the Berning amplifier and maybe mach up with new cables."
As for cabling choices with the Berning ZH270, I would recommend trying what you already have and experiment with the different feedback settings first followed by input tube rolling.
The primary voltage gain stage 12AT7 tubes (the pair closest to the BACK of the amplifier) are where you can most readily tailor the sound to suit your tastes. If your system leans toward the bright/lean side, then a warmer/richer sounding pair of 12AT7 tubes in the primary and/or secondary gain stages would be a good choice.
In my experience, input tube selection in the Berning ZH270 can be as dramatic as selecting cables, perhaps more so once the cables hit a certain level of quality (defined by high conductivity, plausible geometry, low dielectric, low capacitance, and SHORT LENGTH). Since the ZH270, like other good OTL designs, has such a clean and simple signal path -- the lack of interstage capacitors helps here -- and optimally biases the tubes/tube sections, different tube manufacturers tubes sound very different.
The 12AT7/ECC81 tube type was originally designed as a Radio Frequency amplifier. (Ever wonder why many of the top NOS supplies come from ex-NATO stock? They were used in military radars right through the end of the Cold War). 12AT7/ECC81 tubes can perform well in the audio frequency range, and were probably adapted slightly to do so during the post WWII high-fi boom, but all of the vintage manufacturers' designs have noticeable sonic profiles (even different designs from the same manufacturer). The "lush, rich, musical, walk in the forest, etc." sound is quite achievable with the Berning ZH270 by using the lower negative feedback settings in combination with input 12AT7/ECC81 tubes that have those same qualities (e.g. early Mullards, early RCAs, early Sylvania, etc. -- all of which are still available NOS, see my previous post in this thread for sources).
Selecting driver stage tubes (the pair closest to the FRONT of the amplifier) in the Berning ZH270 is also important -- especially to avoid doing any harm. Electrical properties do matter. The 12AV7 and 5965 types were specified for a reason: they work well and can supply current to the driver tubes at peak signal voltages approaching 600 Volts at full power. Many of the dicussions on the web regarding "better sounding" premium alternatives to the humble 12AV7 and 5965 types (e.g. the 7062/E180CC and 6829) are based on listening to these different tubes in preamps at much lower DC plate voltages and peak signal voltages.
"I have heard that the new units are supplied with better cabling and capacitor. Do you know anything about this?"
As far as recent model Berning ZH270 amplifiers being supplied with the upgraded silver wire and upgraded capacitors, I believe that is a premium option that needs to be requested when ordering the amplifier. My understanding is that most buyers have lately requested these options when ordering, based on the feedback here on Audiogon. I purchased mine used here on Audiogon with the silver wire and capacitor upgrades already installed plus the cryo-treated 6JN6 output tubes. I suggest contacting Allan Bhagan for a more definitive answer.
"I’m looking forward to receive the Berning amplifier and maybe mach up with new cables."
As for cabling choices with the Berning ZH270, I would recommend trying what you already have and experiment with the different feedback settings first followed by input tube rolling.
The primary voltage gain stage 12AT7 tubes (the pair closest to the BACK of the amplifier) are where you can most readily tailor the sound to suit your tastes. If your system leans toward the bright/lean side, then a warmer/richer sounding pair of 12AT7 tubes in the primary and/or secondary gain stages would be a good choice.
In my experience, input tube selection in the Berning ZH270 can be as dramatic as selecting cables, perhaps more so once the cables hit a certain level of quality (defined by high conductivity, plausible geometry, low dielectric, low capacitance, and SHORT LENGTH). Since the ZH270, like other good OTL designs, has such a clean and simple signal path -- the lack of interstage capacitors helps here -- and optimally biases the tubes/tube sections, different tube manufacturers tubes sound very different.
The 12AT7/ECC81 tube type was originally designed as a Radio Frequency amplifier. (Ever wonder why many of the top NOS supplies come from ex-NATO stock? They were used in military radars right through the end of the Cold War). 12AT7/ECC81 tubes can perform well in the audio frequency range, and were probably adapted slightly to do so during the post WWII high-fi boom, but all of the vintage manufacturers' designs have noticeable sonic profiles (even different designs from the same manufacturer). The "lush, rich, musical, walk in the forest, etc." sound is quite achievable with the Berning ZH270 by using the lower negative feedback settings in combination with input 12AT7/ECC81 tubes that have those same qualities (e.g. early Mullards, early RCAs, early Sylvania, etc. -- all of which are still available NOS, see my previous post in this thread for sources).
Selecting driver stage tubes (the pair closest to the FRONT of the amplifier) in the Berning ZH270 is also important -- especially to avoid doing any harm. Electrical properties do matter. The 12AV7 and 5965 types were specified for a reason: they work well and can supply current to the driver tubes at peak signal voltages approaching 600 Volts at full power. Many of the dicussions on the web regarding "better sounding" premium alternatives to the humble 12AV7 and 5965 types (e.g. the 7062/E180CC and 6829) are based on listening to these different tubes in preamps at much lower DC plate voltages and peak signal voltages.