can you return any after listening?
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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.
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"
"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."
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?
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.
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.
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 "
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.
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 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. http://www.primaluna-usa.com/prologue-premium-integrated