Where would I buy a "high quality amp panel with in/out crossover filter
that's does filtering properly"?

Hopefully a modern sub panel should have a better filter than the one
included in the Stadium. Rel admitted their early panels were very leaky,
and they gave me a quote for a Rel Storm panel at £400+ vat. yeah right!

Here's a typical new sub amp panel. Digital switching.
http://www.bkelec.com/Diy/DT300.htm

They've also got 500W mosfet model, but it doesn't have output filter.
http://www.bkelec.com/Diy/bsb500.htm

The Stadium is ported? You could look for a model with sub sonic filter
(removes frequencies below tune) If you can find out what the Rel's true
porting is, set the ss filter to that. It'll cut down porting/chuffing from
the port (if you currently notice that)

http://www.svsubwoofers.com/marchandsubsonic.htm

That box is still useful for other passive subs too.

Digital switch version has phono input/output jacks so should do output
filtering (remove LF) contact BK for more info.

I've been thinking about doing the same for my Rel Storm, since that's the
Rel is my "music" sub and it needs a clean filter (which it doesn't have)
and it's quite annoying with the HF leaking through. At least it's not too
expensive, and I can get a aluminium "fake" backplate done FOC by my brother
(metal workshop) :-)

You won't damage the original Rel sub panel, just remove it and store it
away.


The hardware is all in a cupboard with Xantech remote repeaters so
appearance isn't too important.

No problem with amp sub panel then. :-)