Hey Line6-ers.  I've been gigging with my HD500 for a year now and I have had great success with it. That is - until I attempt to use the 4CM with my amp (a Blackstar HT Stage 60).  I've been using my amp as a POWER amp only at shows - all tones are assembled in the HD500.  When I come home and my rig is all dissassembled, I play a lot through my amp without any effects - and I LOVE the sounds coming out of it.  So I try using the 4CM to create new sonic fun - and alas, it sucks the tone right out of the amp.  I tried the solution found here, http://line6.com/support/docs/DOC-2522 and still had no luck, though it was marginally better.

I decided to do some tests for myself to nail down the problem.  I've abandoned the 4CM for now opting to use the HD500 as a pedalboard that all goes into the preamp, since I'm only using effects that are appropriate before preamp.  Even still, I found that simply connecting the HD500 DESTROYS the tone/dynamics/etc. of my amp. The doc aboe alludes to this, but the solution of adding an EQ and rasing the gain 6 dB, then lowering the gain on the mixer by 1.5 dB just bugs me, and honestly, it didn't help much. Using a test tone from a cable tester to measure levels, I found that there is a 2.8 dB (not 6 dB) difference between the HD500 Input and the FX send. (on STOMP setting)  Why? I don't know.  By the way, I saw somewhere that adding effects to the chain (all effects are turned off) will suck your tone out - there is NO difference between how many effects are in the chain - it does not reduce the gain stage by adding bypassed effects - I've checked this thouroughly now.

But the problem of gain loss between Input and FX send was easily solved: Put the FX loop after the Mixer and raise channel A and B each by 3 dB, and pan both A and B to center. This will still work for 4CM users. "SICK!! my tone is back!  This is going to be awesome!" I say to myself.  Then I start scrolling through patches to make the necessary changes to the FX loop and Mixer, and notice - uh oh! 2 of my patches, WITH ALL EFFECTS ON BYPASS, and all other settings identical, sound TOTALLY DIFFERENT!  WTF?

I went further diagnostic diving and found that If I have a chorus, or a fuzz face, (don't know if there are others) in position 1 of the effects chain (bypassed, again) it completely changes the tone.  If they are anywhere else in the chain, or other FX are in position 1 - no problems.  Just wondered if others are seeing this.  Is it a bug in the new firmware, or has it been a bug all along?  EDIT - When I say position 1 - I don't mean Block 1 - I mean the first thing in the chain of effects.

Cheers,

-Tyler