Soundstage disappeared!?

Not sure what happened but this weekend while listening to my system, during a song I noticed the bass went neutral & the instruments disappeared into the back of the room? Up until that time, when I played music it was if I was in the room, concert hall, etc. with the musicians. Not anymore.

The 411 on my system is:

Pioneer PD-F606 CD Player

Pioneer SG9800 EQ

Denon DRA-335R tuner

Audience Ohno Interconnects

16/2 stranded copper speaker wire

8 speakers (8 ohm) Pioneer, Kenwood & Technics

This weekend I'll be able to swap out components to identify the source of the problem but wanted to get you guys opinions on what could be the problem. I'm leaning towards the tuner but will admit I'm electrically incompetent. If it's the tuner, what happened? If it's the equalizer, what happened? Did the speakers crossover? I hope you guys have some way to send me that I haven't already thought of.

Thanks in advance