hi output MM=too little gain

Using Adcom hi output crosscoil MC VDHII cart OR Bang&Olufsen MMC-1 thru Yamaha C2-x preamp/Krell FPB 300/B&W 801Ns, not enough gain thru MM input.
Can turn volume up fully and, although it's pretty loud, it's nowhere as loud as it could/should be. I've installed 10db attenuaters to Tuner & CD to keep all input levels nearer to each other.
Adcom is 2.3mv@5cm/s, MMC-1 is 2.12mv@5cm/s, however MMC is slightly louder despite lower rated output. If I run the Adcom hi output MC thru the MC input in the pre and engage the -10db phono swx, it sounds pretty good w/1K ohm loading selected, but is now too loud + my second TT is hopelessly weak in MM input (-10db swx in rear of pre affects all phono inputs). I need more gain, but i don't want a complicated solution to running 2 low ouput turntables. Phil