Threshold s150 or Forte 4a amplifier?

I have a pair of 4 ohm speakers (2 Peerless High Def 5 1/4 Mid-woofer and Vifa Ring Radiator XT Tweeter in each cabinet) that are around 89 db/ in a fairly small listening room. I have a choice of either the Threshold s150 at 75 watts/channel or the Forte 4a at 50 watts/channel Class A. I am looking for some feed back on both of these amplifiers and suggestions on which amp I should Keep. Thanks in advance for all advise!