Higher powered but efficient amp with the imaging of a Pass XA-25?

I had an XA-25 for a trial driving a pair of Spatial X5’s (97db efficiency). That combo produced imaging depth like I have never heard before or since. But my room is big at 25 x 25 feet and the Pass couldn’t cut it at reasonable levels (too noisy). Now the Spatials are gone, using KEF Reference 1 with Rowland 535 monos. The KEFs are NOT efficient (85 db) and require some real grunt from an amp.

Does anyone know of a high powered (200-500 W/C), high current, balanced amp that is reasonably efficient (unlike Pass) and which can produce the layered depth and finesse of the XA-25? I do not want to go all tubes in my power amps. Hybrid is OK.

I have ordered a tube preamp (Rogue RP-7) to replace my Benchmark LA4. I think that will help but I doubt it will get me all the way there.

Thanks in advance.


Too esoteric to be available for "trial", but a mono pair of BAT VK-255SE would probably float yer boat. 

I’d take a look at the AGD Audion or the LSA Voyager GaN amps as I think they might give you everything you’re looking for.

@soix I did try the Audion's. I didn't care for them. Thin sounding, no grunt at all. Plenty of clean detail, but it takes more than that. I had a Voyager ordered but canceled it. Sounds like a very good amp, but perhaps not much different from what I have now, just maybe just a little more detailed. By all accounts it isn't being described as robust, which is in fact what I want.

@dweller The BAT VK-255SE does sound intriguing. Thanks!

Whoa! Slow down. The description of the sound you gave comes from a synergy of AMT drivers with a nice natural amp like a Pass XA30. If you want that sound you are not going to get it from some KEF bookshelf speakers and the quick choice of a high powered amp. Choice of components trying to achieve a particular goal takes a lot of work and patience.

The Pass amp you had is not noisy… period. If it sounded that way then it was probably an upstream component. Also, you are not going to fill a huge room with bookshelf speakers.

I recommend stopping for a while, taking stock of where you are and where you want to go.  the Pass XA30 is an exceptional amp. You could consider a XA60. But for speakers you either want substantial sized floor standers with an AMT driver, or Maggie’s, Matin Logan speaker or some othe planar speaker. The latter two will require an amp like a Pass x350.8. But it is not going to be as warm as the XA. I chased this dream for nearly 30 years. If you have a $100K to drop, it is pretty easy to solve… I assume you don’t.

I am happy to help, but recognize an amp purchase is not going to get you where you want to go. You need a strategy… and honestly your current strategy is going in multiple directions. If you want to talk off line give me a holler. You can see my current systems by clicking on my ID.



I am happy to help, but recognize an amp purchase is not going to get you where you want to go. You need a strategy… and honestly your current strategy is going in multiple directions.

Pretty much this, you are looking at the wrong component.

...I had an XA-25 for a trial driving a pair of Spatial X5’s (97db efficiency). That combo produced imaging depth like I have never heard before or since.

You already answered your own question here I'm afraid.  


Did you tell us the source you use?

@chorus Bricasti M3 with streaming card (Qobuz) > Benchmark LA4 (soon to be replaced by Rogue RP-7) > Rowlands > KEFs and two Gallo TR-3D subs (via LA4). I have a couple of CD spinners too but really never use them anymore. And I have a Nuprime Stream9 feeding the Bricasti for streaming radio. I am not going back to vinyl.

@ghdprentice This is not a dedicated audio room. It is my living/dining/kitchen room. I tried a pair of maggie 1.7s but they dominated the room physically. Same with the X5s (had to be way out into the room), they did not do well at higher volumes (sweet as they were), and they had an extremely limited sweet spot - stand up and loose all HF. Actually the KEFs with subs load the room better than the X5s with subs, and their dispersion is such that I can enjoy the music virtually anywhere in the room (decidedly not the case with the X5s). The amp I tried was the XA-25, not the 30. Actually, the noise was probably clipping. The main problem I have with the Pass amps is their inefficiency. I do like their sound.

What I am trying to achieve is increased texture without hash and brightness; more robust sound (see next paragraph); phenomenal image depth. I find depth more satisfying than width, maybe because width is good as is.

Since my original post I partially solved my fullness problem, but at some cost. I was using some ribbon speaker cables that improved detail, slam, and imaging, but caused a number of other problems (false and irritating HF textures, metallic sounding HF at certain frequencies). With Soniquil speaker wires (Raven) the presentation is darker but rich, full, and detailed. What is missing by comparison to the ribbons is some slam. I also changed the ports in the KEFs to the shorter ones, though I can't say I really noticed much difference as a result. If anything maybe slightly muddy in the bass (by comparison). I might put the long ports back in. Or adjust the subs roll off down a bit.

@russ69 ​​​​​​​Your suggestions?

If you are looking for more power and the warmth and sweetness of Pass, I would suggest AVM.  They use a MOSFET output stage that is brilliant and offers the kind of textured sound you are looking for rather than the hyperdetailed cleanliness of a Class D.  

The AVM Ovation SA 6.3 will give you 225w of power and is a brilliant match for those Kefs at $10.5K.  

You can get a lot more power out of the Ovation 8.3 line and it has a tube input stage that uses ECC83s but it is much pricier with the 450w SA8.3 at $20K.

Another brilliant alternative is Bricasti but to get the power output you are looking for you would need to look at their monos which are $30K and $33K respectively. 

I am a dealer for both of these brands so I am undeniably biased but I do think they will work for you and resolve your problem.  

@verdantaudio Thank you for the suggestions. After I incorporate the RP-7 and explore its capabilities I will investigate the AVM line.

Maybe Luxman?  I’d be on the phone with Clayton Audio to see if they build a balanced version of their S100 amp.  Probably as good or better than Pass, and although it’s a Class A design there’s a high/low bias switch so you can leave the amp on without heating the house or running up your electric bill — kinda the best of both worlds. 


The Plinius SA100 Mk3 operates similarly, and there’s a nice used one available at what I think is a bargain price if you’re open to used. 


Just a few other ideas to ponder FWIW. 

I agree with @ghdprentice . You are all over the map You have gone from 25wpc to 250wpc and from 97db floor standers to 85db bookshelf speakers. You are trying to fill a big room but that won't be done with bookshelf speakers. Changing amps isn't going to change that fact.

I too have a big room which is also my LR, & DR which is 15 x 32. I fill it with a 65wpc Don Sachs Kootenay and Silverline speakers with subs..Before that an ST-70 w/ 35wpc.  FWIW Don Sachs also has worked with Spatial audio and has their speakers

@russ69 Your suggestions?

Time to shop for new loudspeakers.

Kef likes Plinius sa100 and Mark Levinsons 331 , 332, 333.

@russ69 If I do it will be for a pair of Joseph Audio Pulsar2 Graphene, Fritz Cararra Be, Sonos faber Olympica Nova, or maybe Harbeth 30.2. As you can see I like stand-mount speakers. I think you would be surprised at what I am getting from these KEFs with the Rowland amps. The room is more energized than it ever was with the Spatials. But I know I can coax more from them.

@artemus_5 See my lengthy post from earlier this morning. Yeah, I know about Sachs and Spatial. They are excellent speakers, superb really, just can't live with the limitations. I tried.

@soix Thanks for the recommendations. I will look into them.

@jayctoy Do you have direct experience with these amps driving speakers in the Reference line? Tell me more, like sonic characteristics with these speakers.


If I do it will be for a pair of Joseph Audio Pulsar2 Graphene

You got that right!!!  I’m with you brother. 

Russ +. Nailed it.

Three out four of yours are good choices for new speakers.

I am buying one of them now.

I would swap the SF Olympica for the Amator Electa III.

That would be my ideal choice of those 4. Add a couple nice little RELs

and you are up by 200% from where you are now.

I just changed to a Coda Continuum 8 with my Kef reference 3. It makes beautiful  music. 


Thank you, everyone, for sharing your experiences and recommendations. You have given me plenty of food for thought. I will see what changes the Rogue preamp brings and then make some decisions. If I can remember I will update this thread but it likely will be 6 months or more.

...I had an XA-25 for a trial driving a pair of Spatial X5’s (97db efficiency). That combo produced imaging depth like I have never heard before or since.

The Spatial is an excellent speaker and easy to drive. But since you have to keep the speakers closer to the wall behind them, its probably not a good idea to use a speaker with rear-firing information. If less than about 5 feet to the wall behind the speaker, the reflected information will be interpreted by the ear as harshness rather than imaging detail.

But I think if you liked the Pass, going to a more efficient, easy to drive speaker is the way to go. All amps make more distortion driving difficult loads! This causes them to sound less musical.

With most amps out there, you'll find that tube amps do a better job of imaging and depth than most transistor amps. So the tip about keeping the speaker easy to drive will play very well into the idea of a tube amp if you go in that direction; it will also work nicely with the Pass if you still have it (that amp is fairly low power so you'll need a speaker that has efficiency in the high 90s, like the ZU Audio stuff).

@atmasphere Thanks! The Spatial X5 are really terrific speakers. Clayton and his crew have done a wonderful job with them. And I know they particularly shine with tube amps. But they just were not right for my situation.

One correction: the Spatial's were five feet from the front wall. And they sounded wonderful... if you sat in the very narrow window of a sweet spot. Most natural sounding tweeter I ever heard. But stand up? Lose all HF. Pour on some power? My perception is they don't scale well. And even with self-powered 12 inch woofers they didn't energize the (rather large) room as well as I like.

Mine is not a dedicated listening room. It is a combination living, dining, and kitchen at 25 x 25 x 8 feet. I have music on almost all the time, as I work in the kitchen, eat dinner, read, compute, or less often just sitting to listen. But I want to enjoy satisfying reproduction whatever I am doing. In this situation the KEF Reference is getting me closer to where I want to be, but there is still room for improvement. 

@markmuse If I were in your situation, I would first talk to Duke at Audiokinesis and get a set of his Swarm subs. They would allow you to have proper bass anywhere in the room. The Swarm is 4 subs so as to break up standing waves that otherwise cause bass nulls to appear in the room, often at the listening position. They also prevent too much bass elsewhere in the room.

That would free you up to use a smaller speaker since the Swarms are good up to about 50-60Hz. That would open up a lot of possibilities for easy to drive speakers; if they are easy to drive the amps don't have to be as powerful, and often the smaller amps are the better sounding ones.

XA25 is a great amp partly because it is a class A amplifier.

So, if you want efficiency, you have to move away from class A and also probably away from tube amps.

A best compromise may be other Pass Labs amps which are class AB.

X150.8 or X250.8 (both class AB), will come extremely close to the sound quality of the XA25, and still satisfy your your efficiency & power requirements.