@Jetter, one reason may be that putting the switch in the back results in the amp's noisy internal AC wiring being as short as possible, and being kept away from the small signal tubes and related circuitry that is near the front. Thus minimizing the likelihood of noise coupling into that circuitry.
Obviously many successful amplifier designs have the switch in the front, but putting it in the back means one less potential sonic issue and one less potential compromise for the designer to have to address.
And as a BTW, the same thing is done in the highly respected tube-based Herron phono stage I use. Even though in many setups gaining access to the rear panel of a phono stage may be more problematical than gaining access to the rear panel of a power amp.
Best regards,
-- Al
Obviously many successful amplifier designs have the switch in the front, but putting it in the back means one less potential sonic issue and one less potential compromise for the designer to have to address.
And as a BTW, the same thing is done in the highly respected tube-based Herron phono stage I use. Even though in many setups gaining access to the rear panel of a phono stage may be more problematical than gaining access to the rear panel of a power amp.
Best regards,
-- Al