To add to Wlutke’s comments I would definitely not proceed with the LTA Ultralinear before asking Mr. Salk about the suitability of using an amplifier having a 1.6 ohm output impedance with your particular speakers. My strong suspicion is that the result would be weakness in the bass and mid-bass regions, as a result of the interaction of that output impedance with the speaker’s impedance variations over the frequency range. Especially if the impedance curve of the HT2 is generally similar to that of the HT2-TL, as shown near the middle of this page.
Also, keep in mind that 20 watts is only 3 db more than the 10 watts you are presently finding to be insufficient.
Also, as is the case for most such specs I suspect that the speaker’s 88 db rating is based on an input of 2.83 volts. For the speaker’s 6 ohm specified nominal impedance that corresponds to 86.7 db/1 watt/1 meter. For the 4 ohm impedance the speaker probably has in much of the bass and mid-bass regions, where lots of energy is typically required, it corresponds to only 85 db/1 watt/1 meter. For most listeners 20 watts won’t be sufficient with speakers having such low efficiencies.
Finally, it’s a bit disconcerting that the LTA amp does not have a specified power rating for a 4 ohm load.
BTW, FWIW I’m a very happy user of an XA-25. My speakers are Daedalus Ulysses, which have an extremely flat impedance curve, a 6 ohm nominal impedance, and a specified sensitivity of 97.5 db. I listen primarily to classical music.
Good luck, however you decide to proceed.
Thanks so much Al. Those Daedalus speakers you have are pretty incredible. The ZOTL 10 that I currently have plays incredibly well at reasonable to low listening levels, it’s the best amp by far that I’ve ever heard on the Salks. I’m hoping that 3db 10watts extra of headroom with the ultralinear is enough to give it that little bit extra. But you’re right in that I should probably call Jim to make sure. LTA specifies that 88db is the limit for critical listening and low volume level listening is 85db.
As an extremely happy owner of the Ultralinear LTA I’d say Pass. The LTA UL was designed specifically to work magic with high efficiency designs like Al’s Ulysses and my Apollo’s. With speakers of this type it is off the charts. But matching amp and speaker are crucial so you would be ignoring this truth with the UL. I’d either go with the Pass or consider the LTA ZOTL 40 Reference, which I understand from Mark Schneider at LTA is now very close to the UL but made for less efficient designs. Maybe try both and see which you prefer. LTA has a very generous return policy.
Thank you very much! I‘m gonna do more research. The Pass is intriguing but it’s not as easily available to audition since their return policy isn’t as good as LTA. I have heard great things but at this point I’m totally addicted to the LTA’s sound. Might take your advice and go with the ZOTL40 ref.
Al clearly made a very sound case for why the Pass XA could be a successful pairing with your
It is quite apparent however that you are highly impressed with
My belief is that both of these amps will sound quite good but with very distinct sonic signatures.
The XA25 arrived this afternoon and my very early impressions before breaking it in are that it sounds very detailed, sweet and MUCH more dynamic. I assume this is because of the fact that the ZOTL 10 was struggling a bit with the Salk’s 88db efficiency. I’m very psyched so far. I assume the soundstage will open more as it breaks in but it already sounds layered and wide. More to come when I listen in depth over the next days. Stay tuned.
I've got both right now driving a pair of Tannoy Eaton's (89/8). LTA reference pre in front w/ a Rockna Wavedream DAC.
Can't go wrong with either. I personally prefer the XA25. More detail, faster, more spacious, dense images. Extremely transparent.
The UL has a boogie factor that is incredible. Really captures the emotion/feel/touch of a player well - especially during a solo. UL also has a little sprinkle of inner tube glow which is great.
Absolutely. My room is on the smaller side at 14x20.
I’ve had the xa25 for around 6 months now and have put hundreds of hours on it. Still driving my Salk HT2-TL speakers with the Gungnir Multibit and Don Sachs Preamp. I can say it has more than enough power for my 88db Salks and never seems to loose the incredible dynamics the Pass has to offer, even at higher volumes. The power of the Pass bellies it’s on paper specs by a long shot. Don’t quote me on this but it seems to have more like 100wpc. This all being said, I haven’t heard the Spendor D7’s. I hear the Pass xa25 and Harbeth Super HL5 plus speakers is a wonderful combo and those are low at 86db. The pass seems to have quite the headroom.
What type of music do you mostly listen to, and at what levels?
i have D9s in an almost similar size room driven by a big Pass 250.8 (purchased for my previous less efficient speakers) and love the sound but have been tempted to get something smaller. I listen to mostly folk and rock at avg 80 dbC and the Pass bias needle has never moved. I was wondering about a 30.8 and had never considered the XA-25. I do use a balanced dac and preamp though so going single ended would be a pain for me. That sounds like any interesting pair though and makes me think I can likely get away with much less power since the Spendors are efficient and very easy to drive.
I have owned both the XA-25 and 30.8. I much preferred the 30.8. I did not like the XA-25 and found it fatiguing to listen to for any extended time period even with a tube preamp. My speakers were the Sonus Faber Elipsa SE's. YMMV
I mainly listen to jazz and rock and listen at about the same levels as you mentioned (80db avg). The XA-25 can easily push the Spendors to lounder levels but then it gets too loud for my space.
I also like that the amp is smaller and lighter than the Rogue ST-100. It also doesn't get any warmer than the Rogue.
In my system and room, driven by the matching Rogue RP-5 preamp, the Rogue ST-100 has better soundstage depth.
The XA-25 is comparatively slightly more forward sounding in the midrange and guitars, horns and percussion have better presense.
Through the Spendors, the top end is very smooth through both amps but the Pass has much better resolution of details. I can more easily differentiate between different cymbals and how then drummer is striking them through the Pass XA25
Very interesting. I did notice when I upgraded to the D7s that the midrange, especially vocals, were more forward and in your face. I’m not sure I want it to be any more forward. I’m in a pretty small room (12x13 ft) so maybe the XA25 will not suit my tastes in my room. I’m not really looking for more detail, or resolution. My musical fidelity (KW-500) integrated is providing plenty of that. I want to add touch of richness and maybe a smoother/creamier top end.
The Rogue ST-100 or Pass XA30.8 might just be a better fit for me.