drew the audiophile testing of long time ago also had its foolery as well with many insisting that differences could be heard with the silliest of things being changed.  We often disproved those situations.  The differences in gear I think earlier were large at times but we also came across plenty of situations where there was very little differences in gear too.   Like many power amps sounding the same, good but very similar.   I feel we have similar things today.  Lots of similar sounding things but then something very different and better.   Maybe there is just more if it now.
 
Steve a power amp of even that modest amount of power should be good in the role you are thinking.  Especially of the power supply is slightly over engineered. How heavy is it?  The TV audio in some circumstances is going to slightly less compressed so that amp should be good.  A larger power amp is always going to have a bit more excitement going for it.  I have found in my case the RCA outputs sounded a little better than the headphone out.  Does your TV have any form of Audio Outs.  Many do but people don't realise it. Often they will mirror what the speakers are doing so any input source will usually be output.
 
Bi amping is OK too. The level of the top drivers has to be correctly set.  You do things like measure the outputs from various drivers at various ref level and frequencies while in passive mode.  Something you can achieve with an oscillator, a reference microphone, meter etc .  Then you line up the bi amp level from that power amp to match those passive levels.  Your ear is often a great check too.  I built a special switching device that was smart and it switched speaker levels (with relays etc, intelligently as well eg valve amps getting no open circuits at any point during output changeovers) and line level switching for RCA connections.
 
One experiment I remember doing was comparing these two systems.  In one position I arranged for the bi amped speaker to go back to normal and to be fed from power amp A.  In the B position in an instant mind you, the speakers were bi amped.  The Top section driven from Power amp A to maintain consistency there and the woofer fed from a new secondary power amp B.  All levels were matched of course so the bi amped system had the same frequency response as the passive system.  Instant A/B switching allowed us to accurately balance the bi amp levels better.  Then we got stuck into trying to detect the differences between the two systems over a wide range of material.  Often it was hard to pick what was going on.  Other times the bi amped position sounded a little better.  
 
You certainly don't need it for TV audio.  The benefit of just having your audio reproduced better will be major and much more enjoyable.  It enhances many things but it also highlights poor audio on TV and you will hear more of that. eg poorly mixed TV post audio. 
 
The differences in levels between program and advertised material may also be a little more pronounced.  It is nice to have the remote volume controlling your overall level too as you may find yourself using it a bit more.  I have patched a compressor before your hi Fi amp. (or use the tape monitor circuits for this, this is also a handy thing to do.  Allows you the compressor off alternative)   If you set it right you can get the ads to squash down the volume a bit and the program levels to leave the compressor alone.  It is far better to mute all commercials.   It is the least you can do.  There is too much noise in our world now and TV commercials just add to it.