Got a couple new amps to use on the LS50s. Hopefully will be able to get them setup in the next few days, and see if they are as good a match as that reviewer John Darko says they are.
They are small enough that I can move the amp location out of the amp closet on the front wall (where the old Yamaha amp was), and squeeze them into the Salamander rack, behind the preamp, in the listening room. That will shorten all the cabling. I could place them right behind the speakers, but didn't want all those different cables going across the floor.
Are those Class D amplifiers? Please keep us posted of your results.
I am working on a DIY Class D amp project using a Texas Instruments TPA3255EVM (evaluation module), which is a semi-completed amplifier featuring Texas Instrument's latest PurePath Class D amplification technology. Texas Instruments had a 50% off sale along with free shipping. originally, this module costs over $300, but I was able to purchase it for $74. I just needed to connect a power supply, so I purchased a Mean Well LRS-350-48 regulated switching power supply from Arrow Electronics for about $35. With the 350 watt power supply, the amplifier's output is capable of 140 watts per channel. In the photo, the power supply is underneath the amplifier module.
Details of the Texas Instruments Class D amplifier sale is here:
http://www.diyaudio.com/forums/class-d/309454-ti-class-evm-board-50-promotion.html
Powering the KEF LS50's was no problem at all. When I connected this amp into my system, my wife said this was the best sound she had heard from the KEF LS50's. I have my Audio Research LS7 tube linestage as a preamp, and all the ARC tube magic comes through in all its goodness. The bass is the best I've ever heard from a pair of LS50's, but even better, the mids and highs are clear, smooth and organic. The tonality is warm and natural. If I can characterize the sound best, it's that these small monitors now sound big and full. The soundstage is much larger from the headroom this amp provides, but the articulate and deeper bass create a more solid foundation for everything else. The imaging and separation is further improved, and it really comes through on vocal harmonies and complex orchestral passages.
The other night, I was playing a Reference Recording of Eiji Oue and the Minnesota Orchestra playing Stravinsky's Firebird Suite at moderate volume, and my wife asked me to turn it down as the timpani strikes were coming through to the upper level of our home. For 5.25 inch mid woofers to put out palpable percussion strikes at 75+dB, that just demonstrates how much driver control this high damping factor amp has on the drivers. For this set-up, a subwoofer is really unnecessary.
The amplifier is capable of running in full balanced mode with its differential inputs, so I just purchased a pair of vintage Altec Peerless 15335A bridging transformers to convert unbalanced RCA inputs to differential (i.e., balanced) inputs. The lowered noise floor and increased articulation with the input transformers should really raise the amp's level of performance. There are a few other minor modifications that can be made to further improve the amp's performance.
Because the response to TI's sale has been overwhelming, they are currently out of stock of these amplifier modules. Many DIYers who were able to get these amplifier modules before they sold out have shared the same opinions as mine. Some have even drawn comparisons between the TI TPA3255EVM to their PassDIY "First Watt" DIY clones. I would only recommend working with these amplifier modules if you are adequately trained to work with AC voltages for safety reasons.
