Mike:
I owned Model 6's with batteries. I am also one of those people living in Manhattan, and thus was contending with a power supply that was weighted down with a lot of junk.
I found that, in listening at low to medium volume on what most people would consider a high-resolution system, there was very little difference between the battery and non-battery modes. Surprisingly, it was in running the amp at higher volume with orchestral music and rock that the batteries made a difference. I say "surprisingly" because the batteries are said to reduce available current compared to 120 V. wall operation, and thus would be expected to make the amps sound worse on peak program material. In fact, what the batteries do is provide a very pure source of electricity, and when the volume goes up, they help the amps the remain cleaner at high volumes, as everything is literally magnified by an amp when the volume goes up, including the noise in a dirty power supply. While available power may actually be less compared to wall power, there is an enhanced sense of dynamics due to the ability to achieve greater volume without the sound falling apart. The amps also have a greater ability to delineate between instruments and sounds, which is another thing that tends to be compromised as an amp approaches clipping.
As most people have a fairly dirty power supply, my guess is that the batteries will improve the sound for most people, especially those who listen to bombastic orchestral music and other dynamic source material. Remember also that this amp is truly differential balanced, and will thus sound as it was meant to sound only if run balanced and with the batteries.
I owned Model 6's with batteries. I am also one of those people living in Manhattan, and thus was contending with a power supply that was weighted down with a lot of junk.
I found that, in listening at low to medium volume on what most people would consider a high-resolution system, there was very little difference between the battery and non-battery modes. Surprisingly, it was in running the amp at higher volume with orchestral music and rock that the batteries made a difference. I say "surprisingly" because the batteries are said to reduce available current compared to 120 V. wall operation, and thus would be expected to make the amps sound worse on peak program material. In fact, what the batteries do is provide a very pure source of electricity, and when the volume goes up, they help the amps the remain cleaner at high volumes, as everything is literally magnified by an amp when the volume goes up, including the noise in a dirty power supply. While available power may actually be less compared to wall power, there is an enhanced sense of dynamics due to the ability to achieve greater volume without the sound falling apart. The amps also have a greater ability to delineate between instruments and sounds, which is another thing that tends to be compromised as an amp approaches clipping.
As most people have a fairly dirty power supply, my guess is that the batteries will improve the sound for most people, especially those who listen to bombastic orchestral music and other dynamic source material. Remember also that this amp is truly differential balanced, and will thus sound as it was meant to sound only if run balanced and with the batteries.