comparison between Theta, Bryston, Krell, Parasound

Hey there fellow audians..i have the MAGNEPAN 3.6, CC3, 1.6 and DEF TECH SUPERCUBE REFERENCE for home theatre and music..am deciding between the pre/power combo of BRYSTON 9B SST/ SSP 1.7 ; EAD THEATREMASTER 8800/ POWERMASTER 5300 ; KRELL SHOWCASE PRE/PRO ; PARASOUND HALO A51/ C2..any comments/views?