Didn't you just purchase a SVS subwoofer? Won't you be using it for music? If you cross around 80-100Hz you'll certainly get more punch, but it will be coming from the subwoofer. Why not wait until it arrives and you've had time to properly integrate it into your system?
Just a thought.
Punch never came from any subwoofer. Try listening to any sub with a crossover at 100 Hz or below and see if you hear punch. You won't.
The punch comes from having a low Q sub plus the rest of the speakers having an excellent transient and frequency response, coupled with low driver Qts certainly below 0.4.
To really have punch, requires not playing completely loose with time and phase.
Unfortunately first order crossovers lead to other undesirable issues more often than not, especially in high powered systems. However I believe good audio demands, causing the minimum phase and time shifts required for smooth transitions at crossover and power handling requirements. Just producing a pretty frequency response does not cut it by itself. I don't care what O' Toole and Co. say, phase and time problems are significant issues with loudspeakers and should not be given short shrift.
As far as the 3.5 kHz issue in concerned, a smiley, as its known at 3.5 kHz will cover a multitude of ills. However you are better off with out it.
The problem generally stems from cone break up of woofers and midrange drivers, at and just above crossover, certainly within the octave above crossover. Dollars to doughnuts, this is what you are hearing and don't like.
Unfortunately this problem drives a lot of people crazy, my self and the OP included.
The problem is, it is an expensive taste problem, and the wide bandwidth drivers required do not come cheap. The other way of handling the issue is to hope break up occurs far enough above crossover, that the break up modes can be notched. However there will always be some stored energy in the cone, to make this less than ideal. The truly wide band width drivers required are less in number than the fingers of one hand.
Unfortunately, for most affordable designs, break up is generally starting below crossover frequency. Lowering the crossover frequency means using tweeters with unusually high power handling, and also with under slung voice coils, and with very low Q, so they can be driven below resonance. That creates a lot of expense and keeps the speaker out of the affordable range usually.
That brings up another cause of harshness, driving non low Q tweeters at Fs. If you are not using a very low Q tweeter, then you must have it at least 24 db down an octave below crossover.
There is so much more to a really good speaker, than meets the eye. I just wish there were budget price solutions.