Hi Gents,
Afterlife had right the first time - a couple posts back with the Rocketfish Rear Channel system.
http://www.amazon.com/Rocketfish-Universal-Wireless-Speaker-RF-WHTIB-/dp/B000VEP3XO/ref=lp_2530318011_1_1?srs=2530318011&ie=UTF8&qid=1448679450&sr=8-1
This Transmitter has high impedance inputs so connecting the front outputs from his Denon AVR-S510BT receiver in parallel to the existing Speaker connections will have negligible effect. (According to Page 15 of the instruction manual the input spec is Maximum audio input signal: 10 V RMS into
220 ohms)
(I had one of these systems, and eventually gave it to my Mom when she moved into a Condo and had no "nice way" to run wires across her hardwood floors to rear speakers. I original bought it to "beam" sound out to the backyard to some "Rock" speakers. I actually just bought another Rocketfish Rear Channel system this week as a house warming gift for my friends son. It's parked right beside my chair as I type this - still wrapped in it's box, until I give it to him on the weekend. He too just bought a Condo.)
I am a member of another Audio Site where a Gent connected the Rocketfish Rear Channel system as I described above, and it worked perfectly. Of course with only 2 × 25 W (RMS) into 4 ohms you won't rock the world.
My friend is giving his son a new Sony STR-DN1060 receiver along with 3 Pioneer Andrew Jones speakers (a set of SP-BS22-LR Bookshelf speakers and SP-C22 center channel) for Christmas (my recommendation for his starter system) and I think Calvin should seriously consider these. (Check out the reviews - even Gene liked them.)
I have had a set of SP-BS22-LR Bookshelf speakers connected to an other wireless Rocketfish sytem - Rocketboost™ Wireless HD Audio Starter Kit in my Home Office, and they are amazing for the price paid. If Calvin can still find some SP-BS22-LR on sale at Amazon, or Best Buy, he should be very pleased. (They seem to be less available now that Andrew Jones (the designing engineer) left Pioneer and joined ELAC. Maybe Pioneer is going to discontinue them...) There are lots of new ones on eBay starting at about $100 if Calvin wants to go that route.
You may be thinking what my friends son is going to do with only "Fronts" of a Home Theater Setup. My Friend asked me to help him pick out a decent Home Theater starter Receiver (a couple days before Black Friday) for his son's Christmas present, and gave me his Budget. I picked the STR-DN1060 and got it for $200 off on Black Friday => so he had enough for "some" of the speakers too. To make things even sillier, his son emailed me on December 7th to ask me to help him pick out a decent starter Home Theater Setup, and said "I would like a 5.1 system and I really hate wires.". He said his budget was up to $1500 (Canadian). So playing dumb, I went to see his new Condo and scoped it out, and it can't handle anything but wall mounted bookshelf speakers. Hence the SP-BS22-LR dad bought. So the plan is to tell him to go for the Andrew Jones Bookshelf system (less their Sub - the weak point so probably head to either a Polk Audio PSW505 or a SVS PB1000) when I give him the rear speaker kit Saturday night. He is planning to buy his system beginning on Boxing Day as I've told him it's like Black Friday here in Canada.
Anyway, sorry for the long winded post. But IMHO Calvin's best shot is what I suggested here.