Crumbly/scraping Tone With Time/mod-effects Using A Power Attenuator

[wolbai]

Hi all,

I have posted this Topic also in the DT25/DT50 Forum, because this Topics applies to POD HD 500 + a DT50 amp ...
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I am gigging with the Line6 setup DT50/212 - POD HD500 - JTVs since more than one year now. And for me as Cover Rock Musician this rig works fine.

The Master Volume is set at 1 o clock as a standard level for all my presets (no low volume mode). And I am using the Pre Amp Models out of the POD HD500. At 1 o clock all my used amps sounds very good. Especially the Vintage amps like Marshall Plexi Lead 100, PARK-75 are shinning.But this volume level is heavily loud and just doesn't fit to the overall Band level.

As other users I therefore use a power attenuator (Rivera Rockcrusher) to adapt the overall volume level to the specific environment I am playing (rehearsal, club, hall). I had before a SPL reducer which which I was not very impressed on it. The original function of the Master Volume knob is somehow neutralized, because the amp models I am using are reacting pretty much differently sound wise depending on the Master Volume level I am using (12 o clock and above is the good to me).

My sound problem:
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What I have realized is that when I am using Delay and/or Reverb effects in my signal chain (post amp) which is configured via the HD500, the sound gets destorted in a negativ way by these 2 effects once I am attenuating to a level of -16db and lower: the tone gets somehow crumbly and scraping (hard to describe for me).

EDIT: I am not 100% shure whether this post amp configuration via a POD HD (as described in Line6 manuals) is really POST AMP: this would mean, that all effects are placed AFTER the power section and BEFORE the speakers, so no distortion irritation will occur in the power section from time/mod-effects( my amps power section are all saturated by setting the DT50 Mastervolume = 1 o clock). Does anyone know, if I can 100% rely on that the line6 "post amp" is really a post amp effect setting in its real sense ?

But this is unfortunately the levels I need to reduce the volume to adapt to the overall band volume.

If I do not use these effects, the sound is pretty good at all level attenuation levels. This unormal distortions increases with the level of attenuation.

As I have tried to modify different parameters in the HD500 like GuitarIn-Z, etc. without a remarkable success, I am wondering if one of you have encountered such a sound behaviour and if anyone of you have some ideas what the root cause is respectively how this can be minimized.

Not shure, if I have described well enough, so you can pick it up from there.

Thanks for your support.