Nuforce STA200

I am a fan of 2-way monitors. Most rated at 6-8ohms that I am familiar with have an impedance dip below 4ohms somewhere usually at bass frequencies. I can't help thinking some caution need be applied when using a amp that provides 80wpc at 8ohms and same into a 4ohm load.

Currently I can use my STA200 with B&W 685s, Focal 706s, and the Esoteric MG-10s. All possess the aforementioned impedance dip. I will get back to all after I have more experience with this amp.

mrdecibel or anyone else who may have heard both amps.  I noticed that Audio Advisor is blowing out their Parasound A21's due to the new model A21+.  If I purchase the A21, what and where do you believe would be the level of improvement over my STA200?  Two pairs of speakers are both 6 ohm, one pair being 85db and the other 86db.  I am using pair of SVS subs.  Volume is currently not a problem in my listening area. Thanks in advance for any input.

Before anyone askes, yes I do realize there is a large price difference.

I don't think the Parasound A21 would better within power limits, but it has 3X the power into 8 Ohms and 5X into 4 which could make a big difference not only in volume but also dynamics and openness...I have experience with both but only own the Nuforce...

jl35, thank you for your response, decisions, decisions.