Speaker Sensitivity AND Power Requirements

how big is the man cave
what and how loud do you listen ?
what speakers are you using now ?

It has been many, many years since I've sold Audio,  but I always asked 3 questions,  which tomic601 touched on... 
How loud do you listen?, How big is your room? and what kind of music do you listen to? 
If your room is not too large and you are a chamber music listener or small jazz ensembles, then yes, You will squeak by, but if you are a rocker or like big orchestral pieces,  it won't cut it.  6 ohm impedance on these speakers, so most amps will drive them well,  but I'd look at more power.... If you have a beefy high current amp, 40 to 50 watts will push them, but if you are staying with a receiver, I'd look at 60+....  
I hope this helps, Tim

This might be helpful.  It's not limited to home theater.

http://myhometheater.homestead.com/splcalculator.html

It is a good question.  I have a pair of 90 dB sen speakers in my workshop which is 16 × 20 and it plays to pretty decent volume with a 15 watt receiver but the system runs out of steam fast.

i agree with timlub--i'd look for more power--

Hi again all, thanks for all the good responses. Here are the answers to questions asked.  My man cave is actually pretty big, it's a basement of sorts and is just over a 1,000 square feet.  My gear is a few feet out from one of the long walls and my work table is about six and a half to seven feet from my speakers. These are older Yamaha stand mounters. NS-A 915 YS. They say they need a minimum of 10 watts and can handle up to 120.  I play music while I'm working on my hobbies, It's background music and not dedicated listening as in my main system but I still want the best sound possible. I know everyone here gets that. 
My main taste is heavy rock, Scorpions,Zeppelin, Sabbath, The Who, UFO, etc.  I also love the softer side of rock too, Elton John, etc. Blues, old school jazz, oldies and some classical round out my likes. My cd player in the cave system is a 5 disc changer Yamaha.  This current set up plays nice and it easily gets loud enough as most of the floor is cement.  I did put a throw rug between my table and the system. I was mainly looking at the Wharfedales due to the fact that they are so heavily discounted and I like the sound of my floor standing Wharfedales in my main system.  More comments are appreciated.

Generally speaking, In that room 22 watts usually would not be enough with speakers at this level of inefficiency. The thing is, this speaker does not handle a lot of power and in that regard your receiver is a perfect match. So if you plan to be close to the speakers and only using them for background it will work fine.

I have them, along with a pair of Elac Debut 6s. The Dentons will work best if you feed them some power, even at lower listening levels, the dynamics and punch in the midbass will come through. 

Thanks guys, I think Music Direct has a pretty good return policy. Maybe I should get them and see how they work.  Not ready to replace the receiver. It's in mint condition, generally sounds pretty good, and reminds me of my start in this game. 

@zar IMO I would pick up a pair of Klipsch speakers (your choice of model since they will all work well) that way you are good to go with 22 wats per channel or any other amp.

lak, please elaborate as I have never owned Klipsch. Thanks.

+1 stevecham FWIW I have found that the more power and reserve you provide your speakers the better they perform (without blowing them out of course). There are exceptions to this rule, but in your case I doubt the exceptions apply. If it was me I would want 100W/channel to get everything those Denton speakers have to offer. Don't max the volume and you should be fine.  

no

Thanks for all the replies. Going to pass for now.

Ok guys, there has been a  development so if we could re visit this. I made a bid on Evil Bay on the Yamaha integrated amp I used to have back in the day. It's the CA-810 and has significantly more power than the CR-420. Somewhere around 40 per side more.  I didn't expect to win this bid and frankly was not going to be upset if I didn't get it but there was no bidding war and mine help up. It also included the matching tuner. So am revisiting the idea of going to better stand mounters like the Wharfedale Dentons. Any more choices no more than around 500 bucks per pair? Once again this is for my man cave system that is mainly for background music while I work.  Thanks again.