I've just bought a THD hotplate to use with my JCM800, 100 watt and having some problems...

Whenever I run it on -12db or -16db, the sound is totally unplayable - its extremely fizzy/fuzzy and it would almost annoy you. Some of this sound is even noticeably on the -8db level too!

The amp has recently been re-tubed and doesn't sound anything like that without the Hotplate. Impedance's are all matched and its connected correctly (16ohm setting on head, 16ohm hotplate and into a 16ohm 4x12 jcm800 cab). Unfortunately, I have no other heads to test it with at the moment.

Just wondering if anyone else has had a similar result?

I know that 100watt down to low levels will kill a fair bit of tone and I don't really plan on using that much reduction, but a reasonable tone at that level would be handy on occasion, and I'd rather know if it is the Hotplate that is faulty!
My Gear
Original JCM800
Fender Blues
ADA MP1 Rack

1952 RI Tele
Fender Floyd Fat Strat
Dean Razorback V255
Dean ML79F
Fender Strat, scalloped
Fender Floyd Strat
Ibanez RG550 - 1987 DY, 1990 DY, 2002 BK
Kramer Paul Dean
Danelectro DC59
I've heard the hot plates aren't that transparent so maybe you're just experiencing that.
I don't give a shit if you listen to me or not