The 50 volt restriction is because the connector IS UNSAFE for use with
higher voltages.

..... Phil

Depends what your definition of "unsafe" is. The very same XLR
connectors started life with around 300v rating which they're clearly
capable of and now end up with 50v rating. So the definition of
"unsafe" doesn't refer to working voltage so much as usage. In
addition, there clearly seem to be categories of voltage ratings -
50v, 250v, 300v and such. Connectors aren't rated individually except
for industrial usage.

Best of luck finding a connector which *is* rated for 500V in domestic
use! (Dave Looser)

Yes, exactly. I frankly don't think they exist. Please tell me if they
do! There's a whole raft of industrial connectors but that seems to be
a whole other category of usage.

Reason for two chassis is:
a) Keep noise out of signal chassis - SETs are used by people with
high efficiency speakers.
b) You can't carry an amp with all directly heated triodes. There are
separate DC filament supplies for each DHT. For a three stage SET amp
that's 6 supplies plus heat sinks. For a PP amp it's worse still. Try
lifting that lot of transformers. Two monobloks are possible but
potentially noisy with DHTs and in any case who wants to construct two
HT supplies when one will do.

andy