[sdiy] Relays or reed switches for routing?

[cheater cheater]

Hi all,
this is only tangentially synth related, but I believe some of this
applies pretty well to synths as well.

I would like to build a monitor controller for my speakers. They're a
monitoring set which I'm building up for a future mastering studio.


Here's my current setup:

DAC -> preamp -> active line level analog crossover -> 3x power amps -> speakers

I would like to accomplish a few things.

First of all, because the power amps have very high amplification, I
need to insert attenuating pads in front of them. They need to be
after the xo (crossover) but before the power amps; it's because if
the attenuation happens before the crossover, then the crossover's
self noise starts being noticeable. (however, using 48Vpp op amps, it
has a huge dynamic range). So I need to attenuate 6 balanced signals
(later 8, once I change the electronics to 4-way amplification). As a
certain level of attenuation might be good for long term listening,
and meanwhile you might want to listen at higher volumes every now and
then for checking what a song sounds like at high SPL. So I'd like to
build a switchable pad. This is for voltages that are up to 50V. I'm
not sure what to use here: relays, reed switches, or something else? I
don't want to use any semiconductor based system as this is for
mastering, so a) fluctuations in resistance will mean differences in
levels and b) additional distortion is not good.

I'd be looking for something that's able to be switched quickly and
efficiently, but is also quiet, and won't need replacing very quickly.
Having loud "thock" happen during monitoring would be disruptive to
work, as you really want to listen to the music itself.

Second of all, I'd be looking to build an output switching system for
hooking up the speakers either to the 3-way amplification system, or
to just one of the amplifiers, as a 1-way amplified speaker. This is
to simulate different ways of listening to the music. I understand at
this point, this will require handling of high currents. The largest
of these power amps is able to produce up to 900W. I would most likely
be automatically turning off these amplifiers before re-routing the
outputs, but I understand that any relays or reed switches still need
to be able to handle the current going through them during operation.


I would appreciate any suggestions. What do I use: relays? reed
switches? some sort of mechanized throw switches?

Thanks