I wouldn't think so, but I'd think it best to try and get the coax at roughly ear height in your listening position. I have a center coax and have them on M&K stands at ear height when seated. Just comes down to proper setup.
KevinH, did you ever do any review comparing your M&K setup to you JTR 12?
I have not logain. Mine are all Triple8s by the way. The center isn't even hooked up. I'm still waiting to sell my house so it's just a temp. 2 channel system until I can set up a full HT again. For music though they sound awesome and throw a bigger soundstage than did the S150s which are more directional. Still can't wait to listen to them with a full HT setup and a good soundtrack. I'm trying to be patient.
Epson 5020UB 1080p 3LCD projector
Screen Innovations Black Diamond Zero Edge 1.4 110" 16:9
Marantz AV8801 pre/pro
Wyred4Sound 5-channel amp
JTR 3TX LCRs
JTR Single8 HT-LP surrounds
twin JTR Orbit Shifter LF subwoofers
GIK Acoustic room treatments