With an application like this, you would be better served with either an integrated amp or a 2-channel receiver. If you just go with a power amp, you won't have any control over volume other than with the ipod itself. A receiver or integratred will include the pre-amp section, giving you volume control (possibly with a remote control as well, which would be beneficial here) Would also give you balance and possibly tone controls which you might be interested in. Also the headphone output of an ipod, while it will work, isn't ideal for driving a power amp directly and may sould a bit better driving the input section of an integrated or receiver. Lost of good inexpensive two channel integrated or receivers out there, including those mentioned.
Looks like Ascend sells or or has some relationship with Harmon Kardon. There is a two channel receiver on the site that has decent specs. A basic receiver from Denon, Onkyo, etc. would also be just fine for your purpose. No need to ovrespend here - your source is already compressed audio (nothing wrong with that) so don't go crazy on an audiophile grade amp. Your speakers are easy to drive, don't worry too much about power output of the amp.
Never heard Ascend speakers, they look interesting. The subs looks great with excellent specs.
I have a Samsung mp3 player driving active Dynaudio spekaers, sounds great.
