The issue I have with the OHM 5s is largely attributable to my L shaped room. Bass levels are up to snuff with the 100.3s in the smaller room towards the front of my main listening area but drops off further back. This is the L shaped room with thin carpeted concrete foundation floors where the OHMS sit in the short end of the L firing into the long length, where most listening is done (see my system photo with the Jack Russell Terrier adornment). In the short end of the L and just in front, bass levels are good...further back they drop off.
I have the Ohm 4XO cabinets with the Walsh 5Mk-2 drivers on them in a room that's 16' X 24'. The speakers are centered on the long wall and spaced 6.5' from each other (center to center). There is only about 11' of back wall though, because of the open format, I have no idea how this is affecting the bass response. Maybe it's a trade-off, bass not as good as could be but less standing wave problems.
Some years ago I called OHM and asked John what amp. he would recommend that would make these speakers sing, he recommended the Sunfire Signature so i picked a used one up on Audogon and a used Legacy preamp.as well and have (on occasion) had it up to 75% gain, they handled the power without a problem.