Connecting class D amp to high level input on subwoofer

High level inputs on subs are high impedence, generally 100k and as such present no appreciable loading on the amp so you should be fine. 

There is something different going on with a class D and a normal class A/AB amp. I run a W4S STI-1000 with an REL B1 sub and use the speakon connectors but you must do as Bel Canto's diagram years ago suggested and use the special cable with capacitor. You can do damage if not careful.

Bel Canto put out info on this showing the use of one 10uF 100V Bipolar film or electrolytic capacitor in the amp's + output leg to the sub's + input terminal. This was for the e.One amplifiers with balanced bridged operation.  They say NO to hooking a sub's ground (-) connection if it is actually a real ground.

With the three lead Speakon plug I wired one of those capacitors to each of the amp's positive terminals left and right. I have a ground from teh amp's chassis attached to the ground leg of the Speakon 3-wire cable.There is NO sub connection coming from either - speaker terminal on the amp, left or right. This has worked fine for years.

It was tricky at first. Good luck.

Yes discovered that the class D amps are different.  Thanks for the info from Bel Canto. Unfortunately the Von Schweikert subs do not have a speaker on connection. Found some info stating that if the sub inputs do not go to ground I am fine and detailed the way to test for that. 

I apologize for not checking out your VR subs first. Based on having both R and L connections with + and – legs (full speaker connections) I’d suggest looking at, or checking about using the specified capacitors between your bel canto + speaker output terminals (they’re not hard to wire or solder, or find and buy) and the two + speaker inputs on the VR subs.

If this holds, you’d attach a chassis ground from your amp to the – speaker inputs (L&R) on the sub. (Nothing from the Bel Canto’s negative – speaker outputs either channel.) Not positive but this seems the same as I use. Other help?

I talked to John Stronczer at Bel Canto he said no need for the capacitors for my particular amp.  Seems I need to determine if the - post on the sub is shorting to ground.  This can be done with a multimeter. Found this on the web.

Thanks to all who posted. Here is an update. I spoke with E.J. at Wyred 4 Sound and he told me to use a multimeter to measure Ohms at the subs speaker level input.

1. Measure from Pos to Neg on eacdh channel
2. Measure from the left and right neg. to plate amp ground, which I was able to use the outer ring of an RCA input jack.
3. Measure from left to right neg speaker inout leads.

He said they should not be zero. Well he was right, the left and right negative posts measured 200 Ohms across each other and 100 Ohms to ground for each one. The hot leads measured OL to ground, and OL to each other.

John said to do this and get back to him. I now won't get the subs until Monday and will try this.  It appears that if there is no continuity to ground from the high level inputs I'm good to go. Balanced output from amps to balanced input on the subs.