Itching for better sound

Pretty happy with sound through my Sennheiser HD700s listening through headphone amp to classical CDs on Marantz CD6006...but too much headphone listening makes my ears buzz, so I want to start listening more through speakers.

Could set up either the Marantz or a NAD 516bee cd player, connected with RCA to an old Denon AVR1404 receiver to speakers.  My PSB speakers are fair.  What I want to know is how much will a pair of Kef LS50s improve my sound?  Is my $800cdn (used) better spent on something else--other speakers or another component?
No shostakovich it won't. Change the experience maybe but not the quality. Save up till you can get yourself a good set of high efficiency loudspeakers like Klipsh Heresys. You will get a lot farther with that old receiver. Enjoy your phones for now and save.

Thank you.  Just took a look at those Klipsch Heresys.  They look gorgeous, but the "made to rock" slogan on the website gave me pause.  I'd love to know whether people think some speakers are better for classical music than others.  I don't want "made to rock" unless it's a Mahler kind of rocking.  Think the "hammer blows" in his 6th.
Shostakovich knew how to rock. Take the tenth as an example. A good speaker will play anything. I think what they mean is the little speakers will play very loud with minimal power. Put subwoofers under these speakers and you can make a very sizable presentation. If you really want to knock yourself out the back door with say, The Firebird check out the Cornwalls (also Klipsch) Both these speakers are very detailed without getting harsh. You get a lot of speaker for the money and most importantly it does not take huge amounts of power to drive them. The speakers that are noticeably better are way more expensive and generally less efficient. These you will be able to drive fine with your old receiver until you can afford to upgrade your electronics. A 60 watt/ch tube amp would be perfect:) 
Another option I have is to get powered speakers and to connect them through optical direct to Marantz CD player.  Any suggestions on the desirability of this and appropriate speakers that would trump the PSBs running through that Denon?
i agree that your avr is the limiting factor--i'd look at the dynaudio xeo 2 powered speakers, which are $800 new--very impressive
Thanks for the suggestion.  I will look into that.  What do figure would be the best way to connect these to the Marantz CD6006?  Optical?  The cable's going to be about 40ft.

Do others agree that this is going to get me better sound than the setup described above?
40' may be a long run for optical + you don't know if the dac in your cdp sounds better than the one in the powered speakers, so i'd try rca as well and compare
Your receiver really will be a limiting factor with whatever speakers you choose. The Klipsch are very sensitive and your receiver will drive them. The KEF LS50 requires a good amp with sufficient power to get the best out of them. These speakers have a different sonic signature and I would suggest you listen to them to see which you prefer. 

A speaker at the $500 price point that I would suggest is the Wharfedale Denton 80th. They are available online and you can return them if you don't like them. I actually preferred them over the KEF LS50 and I am a long time KEF fan currently running several different KEF speakers in 3 systems. 
I haven't heard one, but the latest Outlaw Audio RR2160 Stereo Receiver at $850 gets great reviews.  May be your biggest bang for the buck and tie what you already have together.
Klipsh?  You have got to be kidding.  Since when are they an audiophile speaker?  Unless, you like your ears to be drilled with high frequencies.

I agree, save up your money until you are ready.
Klipsh?  You have got to be kidding.  Since when are they an audiophile speaker?  Unless, you like your ears to be drilled with high frequencies.

I agree, save up your money until you are ready.
I recommend a Yamaha A-S801 integrated amplifier. If you don't need the Video features of your AVR this will make your PSB speakers sound brand new and will pair well with any other new speakers you bring in.

I addition you can try the built-in DAC on the A-S801 via optical/coax from your Marantz - you might prefer that clean Sabre sound. Two upgrades in one!

Yeah, the AVR has to go.  There’s a nice Rogue Audio Sphinx V2 at US Audio Mart for $850 that would really help your PSBs sing and is good enough to not be out of place even with a significant future speaker upgrade if/when that happens.  Best of luck. 
+1 to @soix

Rogue Audio makes nice products at decent price.

I have nice collections of headphones including Stax 009s, Raal Sr1a and HD800s.

But headphone can not beat speakers in dynamic illusion although Sr1a get close to speaker.
+ for the Rogue

i own a pair of Cornwall’s, they would not be my first choice for The Ressurection, but they also would not be the last....

btw I caught a Cleveland Symphony performance where they used a large leather clad sheet of plywood and a sledge for emphasis !!!! 
Have fun, get out to dealers and listen, enjoy the music
Was that plywood/sledge for the famous "hammer blows" in Mahler 6?  I'll be attending Mahler 2020 festival at the Concertgebouw in May--NY, Berlin, Vienna Phil among others.  That should whip even the finest audiophile equipment, and it's why I can't afford any major upgrades just now.

Thanks to everyone for their input.  I will keep my ears out for the right amp!
As for the Rogue, I really need something to which I can connect two sets of speakers.  Is that an audiophile no-no?

Would welcome any thoughts on these three amps: Yamaha A-S801, Marantz 6006, Cambridge Audio CXA-81.
I would go for the Yamaha, it has the most power of the three and the lowest price. The Marantz seems a little under powered. The Cambridge does not have tone controls which may or may not be an issue for you. Of course the sound quality is the most important and I have only heard the Yamaha and it seems to be a pretty nice sounding amp.
My A-S801 really makes pianos sing - and the inbuilt DAC really pumps up the value/performance ratio. 
D'yall think my non-audiophile ears are going to hear a dramatic difference between my current Denon AVR1404 and the Yamaha A-S801?
Short answer, yes you should hear a significant improvement by swapping the AVR for an integrated stereo amp. But I have to ask, why do you need two sets of speaker output terminals?

Anyway, with the Denon you’re not only using a compromised amp but also, at least as importantly, a compromised preamp. By compromised I mean that they’re designed to meet a competitive price point, so expensive yet crucial electrical components — such as power supplies, etc. — are usually of lower quality and significantly affect the quality of the resulting sound reproduction. The amp/pre sections are also bombarded by a litany of other noisy electronics necessary for an AVR to do all the things it needs to do (DAC, digital signal processing, etc.) as they all reside in the same case. So by adding a dedicated integrated stereo amp you get higher quality components, more focused and accomplished circuitry and design, and less inherent noise you’re likely to hear a notable improvement, especially as your speakers are refined and revealing enough to convey such differences. Things such as bass weight and definition, cleaner and extended treble detail and air, image separation and solidity, soundstage width/depth/height, ability for sound to separate from the physical speakers themselves, tonal richness and shadings, micro/macro dynamics, as well as overall transparency should all improve markedly. And when you combine all these improvements it results in a totally different and more believable, involving, and more rewarding listening experience.

Lastly, one of the reasons I recommended the Sphinx is that it comes from a very highly regarded designer/manufacturer with an impeccable reputation for service, and it benefits from the trickle down of technology and design implementation from its more expensive siblings in the Rogue lineup. And although it’ll sound great with its stock input tube, you have the flexibility to change the inexpensive tube to custom tailor the sound to your specific liking. Moreover, it’s good enough to reward you for any speaker upgrades you make in the future, and as the Sphinx doubles its power output to 200Wpc at 4 Ohms impedance it has the juice to easily drive just about any speaker you throw at it. But, amps are still a personal choice based on individual personal tastes, so I thought this excerpt from a CNET review of the Yammy A-S801 might help put things in perspective and help with your decision...

“While the A-S801’s competence was never in doubt it lacks the more "robust" character of the $1,295 Rogue Sphinx amp’s sound. The Sphinx is a cool running vacuum tube/Class D hybrid design that sounds like a classic 1980s high-end integrated amplifier. The Sphinx is rated at 100 watts per channel for 8 ohm speakers, 200 watts per for 4 ohm speakers. There’s more body and soul to the Sphinx sound, the A-S801 is tonally cooler and lighter on its feet. Which one is better? I prefer the Sphinx, but tastes vary, you might go for the A-S801.”

Hope this helps, and best of luck.
Thanks so much for that thorough explanation.  As a non-audiophile, it's hard for me to figure out how amp and not speakers will make the biggest difference, but I've listened to all the people here.

For a number of reasons, I often like to have the same music playing in two rooms, hence the two sets of speakers.  
Heresy IIIs are indeed a high end speaker and reveal what's in front of them beautifully and very efficiently with, of course, all sorts of music from BB to Britton (no good speaker system is "music specific")...very balanced and coherent sound, and now perhaps less expensive since Heresy IVs were released recently. A bargain great sounding speaker. Don't trust the opinions of old white dudes in red ties, have a listen for yourself.
The A+B Speaker terminals is the only thing holding me back from trying a Sphinx - I've heard consistently great things.

I use the Yamaha with 4x 6ohm speakers in a large, 500 sqft room. Sometimes I turn it up really loud. It doesn't break a sweat. 

My upgrade path was Yamaha AVR -> Marantz PM6005 -> Rotel Int -> Classic NAD Int -> Yamaha A-S801.  Those other amps didn't last long in the room.  The Yamaha has been here for 2 years.

The Yamaha leaves little to desire.  Good luck!
In regards to whether the amp will make a big difference - I assure you - you will be amazed.  It will be as if you bought new speakers as well.  That's how I felt.  Cheers!
Leemaze -
Just curious, what speakers are you driving with your Yamaha A-S801. I was thinking of getting one to simplify my office system. I did a listen a while back and was pretty impressed with the amp. 
Hi ljgerens,

It is rock solid.

Wharfedale Diamond 10.7s and Wharfedale Diamond 220s