Help in selecting 1 of 3 amplifiers

I’ve narrowed my choices for a new integrated amplifier to 3: Peachtree Nova 125 se, Rogue Sphinx, and Wyred 4 Sound mINT. The amplifier will be paired with Kef ls50s and play mainly digital files either from an Onix XCD-88, or an SMSL Sanskrit external DAC (won’t use the external if I get the Wyred or the Peachtree). What are your thought on choosing one? I can’t audition any of the amps where I live so I’ll be buying it blind, umm unheard?

the room is on the larger side since it’s a combined living room and kitchen 15’x25’. The speakers will be in a built in wall unit. Acoustically the room is pretty good, even our Samsung tv sounds darn good, so I’m not worried about the ls50s being unable to fill The room. I’m trying to keep the cost down so I’ll be picking it up used, if Zi can find one. Help me pick the winner!
can you return any after listening?
I've owned several Peachtree amps and had reliability issues with each of them. In addition, I submit there is some type of abnormality with the mids/highend of the Peachtree amps. My friend went from a Peachtree 220se to a Rogue and he couldn't believe the difference between the two...he quickly sold the Peachtree.
Go Rogue.....  I have had good luck with several tube / mini monitor combinations.   Those speakers have a great mid range that will exploit the virtues of tube amplification.   Their support is supposed to be good, maybe others can comment 
Like most speakers today, the LS50 has an impedance curve that favors solid state amps with their low output impedance.

The impedance curve of the LS50 has a pretty big and wide peak from 200 Hz (4 ohms) to 1.5 KHz (13 ohms) to 3 KHz (7 ohms). This makes for a poor match for a typical tube amp with a high output impedance, especially in the midrange.

To see what a good match looks like check out this Thiel:

However, it may not make that much difference since the little LS50 with its 5.25 driver in a tiny cabinet will be pretty lost in a 3000 cubic foot (15' x 25' x 8') space.

The distortion characteristics of the LS50 are as expected for such a small speaker; it increases steeply below 200 Hz.

Use a solid state amp, sit close, keep the volume down and biamp with an active sub (i.e., high pass the LS50).

Bob is correct, lovey speakers the LS50’s but if you want the best from them they need a bit of current from an amp, because of the combination of 5.3 ohms and –41° at 135Hz which could equate to an EPDR of around 3ohms as seen by the amp.
As an example for a small integrated, I can think of the little old Krell 300i that would suit.
Stereophile: Krell 300i " 250W peak program, 8 ohms, grew to 400W peak into 4 ohms with 620W peak available into 2 ohms. These figures are backed by ample peak current, measured at approximately ±45A"

Stereophile Quote:
"The electrical phase angle is generally mild, but the combination of 5.3 ohms and –41° at 135Hz, a frequency where music often has high energy, will make the speaker work at its best with a good, 4 ohm–rated amplifier."

Cheers George

Again, I am blown away by the knowledge base of the members of Audiogon.  Thank you all for your thoughts. Bob I didn't realize you were still around. I recall your posts on the Qinpu amplifiers several years ago. I'm finally parting ways with my 1.0x although I am curious to see how the ls 50s would sound with it. 

Any others out there with opinions on the Rogue, Peachtre and Wyred4sound?

I switched between a Parasound A 21 and 20-watt Cary CAD 572 SE tube monoblocks that are MOL on permanent loan to drive a pair of LS50s, and was surprised at how well the Cary amps sounded with those speakers.  (I plan to compare them to an Ayer VX-5 Twenty that I hope to have soon.)

What George pointed out regarding the LS50s low impedance load is not the issue I was addressing. To ensure a balanced level across the audio band from high output impedance amps, the load needs to be resistive. With high output impedance amps the frequency response of the system will follow the impedance curve of the load. This is why JA presents a graph in his measurements showing the frequency response with a simulated speaker load.

For example, a PrimaLuna amp:

Here's the simulated speaker load:

Compare Fig 4., the response of the simulated speaker load, to Fig 1., the response of the PrimaLuna. Note the same peaks at 55 Hz, 1500 Hz and 8000 Hz and the troughs in between.

This is a tail-wagging-the-dog situation that seems to be forgotten when folks shop for amps. A high output impedance amp will sound as different as the difference in the impedance curves of loads its driving.

I think the impedance peak in the midrange of the LS50 is something to seriously consider when shopping for a matching amp. I would not use a typical tube amp with the LS50.

Bob are there some amps that come to mind that may pair well with the ls50s?  <$1k used price would be good
I mislabeled Fig 4 in my previous post... it should have read: "the impedance curve of the simulated speaker load"

Sorry for any confusion.

-- Bob
autre, based on your other thread you're looking for an integrated amp. In that thread I suggested the wireless active LS50. That would solve the amp matching issue, but I don't know if that fits your source(s) and/or combined budget (speakers + amp).

Do you already own the passive LS50?
I suggested the wireless active LS50.
Then you at the mercy of class-D amps, like em or hate them.

Cheers George
If you don't already own the LS50, you might consider the Wharfedale Jade 1 or Jade3. Both are 3-way designs and I think would be better suited to your sized space than the LS50. Either are less expensive than the LS50 which would free up dollars for the amp.


It's probably unfair to group all class D amps together and what matters is the end result. The active LS50 has many advantages over the passive model. I think it would be a better fit for the space than the passive, but it's still a 2-way and small.
Thanks Bob, yeah I already own the ls50s. Got a great deal on a new pair so I jumped on it. So unfortunately the actives aren't an option. But yes, if you have suggestions for the integrated please let me know
Later model to the one I mentioned, but still with Krell low impedance drive ability.

" Krell touts its massive 750VA toroidal transformer and 38,000 microfarads of capacitance as among the more potent ever incorporated into an integrated amplifier.  –Neil Gader "

Cheers George


Since moving to active speakers about 10 years ago, I don't pay that much attention to amps any more. I recall that integrated amps typically don;t provide both main amp inputs and preamp outputs. So, it's not possible to insert a bass management controller between the preamp and amp sections. I think that would be a benefit for the LS50 when using a subwoofer.

Bryston and NAD are two companies that I remember did. There was a Rega model and a Creek model that did as well. But, that was a long time ago.

Marantz's PM8005 looks competent enough and provides both connectors. Parasound's Halo integrated has bass management builtin.

Sorry I can't be of more help. Good luck with your search.

-- Bob

Vincent 237

I've paired the kef ls50 with a yamaha a s1000 integrated and love the sound. The Yamaha is built like a tank and drives the kef's nicely and can be had for around 1000. Strictly old school.
What is your budget? For my money you can't get a better DAC at ANY price than the PS Audio DirectStream DAC. Sublime. Converts digital to DSD which simulates analog on an oscilloscope. Go to their website and check out the reviews, videos, etc. I run Nordost Heimdall 2 balanced cables out from the DAC to a Krell Foundstion and it's pretty sensational....and reliable.  

I suggested the wireless active LS50.
Then you at the mercy of class-D amps, like em or hate them.
The tweeter is Class AB powered and the woofer is Class D powered. 
The LS50 active has a 12 month warranty...a lot can go wrong with active stuff crammed in a tiny spot. 
I've heard the ls50 with an NAD 326BEE and was pretty impressed. I imagine the Yamaha AS501 - 801 series would work well too. I recently purchased a Teac AI2000 used on here that I intend to eventually pair with ls50's and expect similar results. 

Try the Ming Da tube intergrade amps. There rugged and reliable. Dead quiet and clear as a moon lite sky. Bias is easy and do it once every 6 months , like my sex life !
I had the KEFs ls50s paired with the Rogue Sphinx for a while.  In my smallish room, it was a bright combination.  (Some people love this pairing, but I've also noted others who reported it was bright.)  I now have my KEFS paired with the Vinnie Rossi LIO, which is a magical combination (although the LIO is quite a bit more $$$ than the amplifiers on your list.)  Closer to ones you are looking at, I have heard the Schiit Ragnorak is a great match.  Since Schiit offers a trial period, it would be easy to try it out.  Good luck!  Margot
Not on the OP's original list, but another +1 for PrimaLuna. A friend's LS50's really sing with this integrated. Seems to be a popular combination.