MeanGene,
I am running my 990 with balanced connections to my 2200's and 7500 and I do not experience any thumping at all.
I can change inputs and mute and it is deaqd quiet.
I get the inital small click or pop when everything is first turned on but that's it.
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Epson 3500 3D projector
93" Carl's Place Flexiwhite DIY screen
Outlaw 976 Pre/Pro
Outlaw 7500 for center and surrounds
2- Emotiva XPA-1Ls for LF/RF duty
2- Outlaw LFM-1 EX subs
Oppo BDP-105 Blu-ray/DVD/SACD player
Outlaw LCR (Snell Labs) for center channel duty
Tekton Lore monitors L/R
4- Emotiva ERD-1s surround speakers
Monster HTS3600MKII power center