[kevin_jazz]

I recently purchased the excellent LS50, which is currently being powered by a pioneer a/v VSX 42. I'd like to upgrade the pre/amp. I'm attracted to tube designs but do not rule out hybrids and SS. On paper, the low sensitivity of the LS50 suggests that low-power tube amps would not be a good choice. However, I noted with interest that at AXPONA 2014, KEF paired their LS50 with a PrimaLuna Prologue Premium (35-45W pc). So, I assume that they wouldn't display them if they didn't think they played well together.

http://audio-head.com/kef-room-axpona-2014/

I'd love to hear from other LS50 owners who have matched them to tube or hybrid systems. My room is medium size with a fair amount of stuff. I like the music cranked a bit higher than conversation level but far below concert level (I think our ears saturate at that level).

Thanks in advance for your input!

Let me know if there's a more appropriate circle for this question.....

[mnilan]

Kevin:
I can't answer your question.  However, I was on a speaker and integrated amp search last year and went to a bunch of B&M showrooms and to the Toronto and New York audio shows to listen to speakers and amps.  The Kef LS50 was one of the speakers that my wife and I really liked but ultimately, we went with the Nola Boxers.  The Kef was a bit bright to us (our living room has one entire side that is windows) and we were afraid that it would not be able to deal with its large size.  The Boxer is a bit more efficient than the Kef (90 db vs 85) but we have tried four integrated amps that we like with the Boxers (8 ohm power specs, in ascending order of preference):  Creek Audio 5350 SE (SS amp outputting 85 wpc); Antique Sound Labs AQ 1005 DT (300B SET tube amp outputting 9 watts); Rogue Audio Sphinx (hybrid integrated outputting 100 wpc); and Audio Space Galaxy 34 (EL 34 push-pull tube amp outputting 16 wpc in triode and 32 wpc in ultra linear).  In general, we prefer the tube amps to the SS.  But the ASL 300B just doesn't quite have enough juice for the Boxers and I think it would drive the Kefs but you would have the same problem - it gets a bit congested (especially in the low end) with complex music (e.g., orchestral) and loud rock 'n' roll doesn't have the "slam."  Having said this however, we really like the Sphinx.  Its tube pre-amp makes for a very sweet sound with the Boxers and it has plenty of control for complex recordings.  The Galaxy 34 is even better though as it sounds great with jazz and classical in triode mode and rocks out in ultra linear mode.  It maintains the great mids that tubes are known for but has the power to rock out.  There may be other tube amps that would also work with the Kefs but the Galaxy 34 had the right combination of features with a reasonable price that (under $2K) that worked for us.  So, I think either the Sphinx or the Galaxy 34 would be great with your LS50 speakers. 

I don't think our time schedules are in sync but as soon as my hifi budget is replenished (probably within a year), I will get some LS50s to find out - but that will likely be too late for your needs.  At any rate, I wish you luck in your endeavor.
Mike

P.S.  There is a Kef LS50 discussion in the Modern Hifi area of AudioKarma that might be of interest to you.

[groovybassist]

Kevin:

I don't have any experience with the LS50s, but do have recent experience with Line Magnetic's LM211ia integrated amp.  I used it to drive my Merlin TSM-MMMs and it was a great combo.  If you're playing level is moderate, I'd imagine an EL34 amp would drive the LS50s fine, if you like EL34 sound in general.

I've moved to a new place and have a puppy on the way, so will be selling my LM211 very soon - just haven't gotten around to posting it.  It's maybe 4 or 5 months old, so should move just fine.  With the puppy coming, I've switched to the Red Wine Audio Signature 16, which is a phenomenal piece of gear with the Merlin's.  Might be worth some correspondence with Vinnie to get his feedback on pairing it with the LS50 as it's only 16 watts/channel - it is an amazing 16 watts though.

Good luck in your search.

-Mike

[groovybassist]

One other aspect of the RWA 16 I like is you can get off the uber power cord and power conditioner train.  I've been on it and believe there's some efficacy to it, but it's nice to have components that don't care about these tweaks, which can save a lot of money and trial-and-error.  Since power is charging just the battery in Vinnie's RWA gear, nothing special is needed beyond the power cord he supplies with the unit - a welcome change.

-Mike

[RDavidson]

The KEF's do like a bit of power (current, not necessarily watts).
I wouldn't be at all surprised if the KEFs worked well with a medium power tube integrated.
What you really need to consider is how large your room is and how loud you typically listen.

My room is not very large and I tend to listen near field. Sometimes I like to hook my LS50's up to my Pass 30.5. The Pass is 30 watts into 8ohms and 60 watts into 4ohms of class A power. Only on heavy bass / dynamic peaks can I make the bias needle on the 30.5 move out of class A and into its class A/B power range for short bursts. I don't normally listen to volumes nearly this loud, but every now and then I like to crank the volume a bit. Based on what I'm experiencing / seeing, the KEFs can pretty easily drink up 60 watts of high current class A power (depending on other factors indicated above).

If I were looking at a reasonably priced integrated today, I'd look at the Rogue Sphinx. I haven't heard it, but all the reviews have been VERY positive. Something tells me that it is one overachieving piece of gear. It should be a good match in terms of power for the KEF's. Sound wise, it should be excellent too. The KEF's have a somewhat bright lower treble, which can be a bit much in the wrong setup. The tubes in the front end of the Sphinx should balance this treble energy quite a bit, not to mention, you can roll tubes to subtly shift the balance to your preference.