Your speakers are rated at 200 watts at 4 ohms. The Krell is rated at 800 watts for 4 ohms, so there is the potential for serious costly driver failure in your future. The Krell will give your speakers a little more zing and will tighten up the ported bass, too. Tad doesn't say if the 200 watt power handling of 200 watts is RMS power, average power, music power or peak power. If music power its assumed it includes 6 db peaks or a 50 watt RMS rating. If it RMS of 200 watts then the peak rating might be 800, but I find that impossible for one small woofer. So I lean toward the 200 watts being the music power rating. So having a 800 watt amp is a failure waiting to happen, especially as the amp doesn't have any real protection for the speaker. The Mac on the other hand if placed with in a reasonable distance from the speakers and the wire gauge chart followed in the owners manual will give exemplarily performance and offer protection to the valuable drivers in case of an operational mistake or oversight. The sound will be smoother, a little more laid back, with a potential for long sustained listening with less likely hood of fatigue factor. The bass will be faster and drier with the Krell, but the Mac is no slouch. Proper speaker placement will easily make larger changes than the difference in bass from either amp. From 80 hz up I bet you'll find you prefer the Mac for its presentation.
I don't know about your pre-amp, but Krell expresses concerns about pre-amps in the owners manual you might want to consider. Krell prefers you use their CAST system for the best performance between the Power amp and pre-amp. Krell further says their amp is balanced and to get the best performance should be used that way, where Mac seems to be a little more forgiving in that respect. Service after the sale is another consideration, and you know your Mac can be serviced by any numer of regional centers as well as by the Factory, Audio Classics, etc. When we thought about taking on the Krell line we decided there service polices which frowned on local service preferring factory repair or exchange was frowned upon. So when comparing to 7300's and 2600's at the time we passed. I mean if we wanted that sound we could always sell Yamaha for a lot less money.