Benchmark HPA4 Headphone / Line Amplifier Impressions

[w0000t]

Hey everyone!

I know this topic has likely been discussed before, but I’d love to hear insights from the experts here.

I currently have a Diana DZ and am looking to upgrade to a higher-end amp. So far, I’ve only used portable DAC/Amp setups like the Xduoo XD05 Pro. Now, I’m torn between the Xi Audio Formula S and the Benchmark HPA4.

Unfortunately, I don’t have the opportunity to audition them, so I’ve been relying on reviews and forum discussions. Both seem to be excellent choices and would pair well with the Diana, but since the Formula S was designed with the 1266/Dianas in mind, I wonder if it has an edge. My biggest hesitation is the lack of solid YouTube reviews on the Formula S.

If anyone has experience with both of these amps—or any other suggestions—I’d really appreciate the feedback!

 

[plumpudding2]

Hey everyone!

I know this topic has likely been discussed before, but I’d love to hear insights from the experts here.

I currently have a Diana DZ and am looking to upgrade to a higher-end amp. So far, I’ve only used portable DAC/Amp setups like the Xduoo XD05 Pro. Now, I’m torn between the Xi Audio Formula S and the Benchmark HPA4.

Unfortunately, I don’t have the opportunity to audition them, so I’ve been relying on reviews and forum discussions. Both seem to be excellent choices and would pair well with the Diana, but since the Formula S was designed with the 1266/Dianas in mind, I wonder if it has an edge. My biggest hesitation is the lack of solid YouTube reviews on the Formula S.

If anyone has experience with both of these amps—or any other suggestions—I’d really appreciate the feedback!

I've seen a Xi Audio Formula S on the inside (https://www.head-fi.org/threads/ele...la-s-headphone-amplifier.956765/post-16266142) and it's not very impressive, I would personally never buy one. Maybe it sounds fabulous, I haven't heard it but even topping amps look more impressive internally.
The HPA4 however is imo the best thing you can buy in its price class, absolute transparency, perfect volume control and enough power to drive about anything.

 

[rlawry]

Best I can do since I have never heard the XI Audio is relate my experience with the HPA4 and I agree wholeheartedly with the post above. The HPA4 has vanishingly low distortion and noise and you will hear the most you have ever heard on a recording. Its music is fast, detailed, spacious, and transparent and ruthlessly revealing of mediocre recordings and cheap associated components. That being said, my personal tastes favor tubed gear and musical immediacy which I bought after selling the HPA4. Nothing wrong with it in any way, just a personal preference. I can say that with the HPA4 driving my RAAL SR-1b and its ribbon drivers, the sound was perhaps too much of a good thing since both have similar sonic characteristics.

 

[w0000t]

I've seen a Xi Audio Formula S on the inside (https://www.head-fi.org/threads/ele...la-s-headphone-amplifier.956765/post-16266142) and it's not very impressive, I would personally never buy one. Maybe it sounds fabulous, I haven't heard it but even topping amps look more impressive internally.
The HPA4 however is imo the best thing you can buy in its price class, absolute transparency, perfect volume control and enough power to drive about anything.

Wow those inside photos are shocking.. (in a bad way). I get that's not the whole point and sound matters, but I'm definitely leaning towards the HPA4

 

[rlawry]

Yeah, I agree that the inside of the Formula S is clean but amazingly uncomplicated, even if you account for the much bigger power supply housed in the Powerman.

One thing already mentioned is that the HPA4 uses a stepped relay attenuator so you know exactly the output of the HPA4 to within 0.5 dB. This is great when comparing other components as you can keep precisely the same volume while making the comparison and not allow volume level to affect the result. I miss that with my tube amp.

 

[AnyDave]

Yeah, I agree that the inside of the Formula S is clean but amazingly uncomplicated, even if you account for the much bigger power supply housed in the Powerman.

One thing already mentioned is that the HPA4 uses a stepped relay attenuator so you know exactly the output of the HPA4 to within 0.5 dB. This is great when comparing other components as you can keep precisely the same volume while making the comparison and not allow volume level to affect the result. I miss that with my tube amp.

Yeah, I use my HPA4 as a dual purpose amp. In addition to the standard listening usage, I also use it as as the reference headphone/IEM amp in my home test system, and the stepped attenuator is wonderful for making sure I've got consistent and quantifiable drive levels.

 

[maro65]

Hey everyone!

I know this topic has likely been discussed before, but I’d love to hear insights from the experts here.

I currently have a Diana DZ and am looking to upgrade to a higher-end amp. So far, I’ve only used portable DAC/Amp setups like the Xduoo XD05 Pro. Now, I’m torn between the Xi Audio Formula S and the Benchmark HPA4.

Unfortunately, I don’t have the opportunity to audition them, so I’ve been relying on reviews and forum discussions. Both seem to be excellent choices and would pair well with the Diana, but since the Formula S was designed with the 1266/Dianas in mind, I wonder if it has an edge. My biggest hesitation is the lack of solid YouTube reviews on the Formula S.

If anyone has experience with both of these amps—or any other suggestions—I’d really appreciate the feedback!

Hi, I'm not convinced that the HPA 4 has enough power to drive the most difficult planar headphones, at least in my experience

 

[plumpudding2]

Hi, I'm not convinced that the HPA 4 has enough power to drive the most difficult planar headphones, at least in my experience

My Susvara sounds fabulous on my HPA4, compared to the HM1 it has a bit more separation, is a bit lighter and the stage is a bit smaller but it still hits like a truck. HM1 hits harder but the HPA4 was to my ears easily superior to the Ferrum Oor which is supposed to be a powerhouse. Still I switch between the HM1 and HPA4 regularly as both have their own presentation.

For lower impedance planars it has even more power. Maybe for Susvara or Mod house Tungsten specifically I would buy an AHB2 instead but any other planar the HPA4 will drive it with authority. It has gobs of current available (1.5 Ampere, 6W into 16 Ohm)

In what ways did you perceive it as lacking?

 

[maro65]

My Susvara sounds fabulous on my HPA4, compared to the HM1 it has a bit more separation, is a bit lighter and the stage is a bit smaller but it still hits like a truck. HM1 hits harder but the HPA4 was to my ears easily superior to the Ferrum Oor which is supposed to be a powerhouse. Still I switch between the HM1 and HPA4 regularly as both have their own presentation.

For lower impedance planars it has even more power. Maybe for Susvara or Mod house Tungsten specifically I would buy an AHB2 instead but any other planar the HPA4 will drive it with authority. It has gobs of current available (1.5 Ampere, 6W into 16 Ohm)

In what ways did you perceive it as lacking?

Technologically the HPA 4 is one of the best amplifiers on the market and a reference on certain parameters, but with headphones like Susvara and 1266 with some tracks with high bass content and at high volume it went into clipping, it is true that these are borderline cases but it bothers me, the Ferrum Oor is better but still insufficient to have the best performance with Susvara and similar, even Holo Bliss is at the limit, but speaking of the DZ probably all of these can be fine

 

[plumpudding2]

Technologically the HPA 4 is one of the best amplifiers on the market and a reference on certain parameters, but with headphones like Susvara and 1266 with some tracks with high bass content and at high volume it went into clipping, it is true that these are borderline cases but it bothers me, the Ferrum Oor is better but still insufficient to have the best performance with Susvara and similar, even Holo Bliss is at the limit, but speaking of the DZ probably all of these can be fine

ah yes, with Susvara it has about 1.5W which you can reach with a bass shelf and/or very high volume (at 1.5W it produces 115db). I listen fairly low volume, I once tried to see if I could get it to clip but for me the sound got above the pain threshold before clipping occured. If you are a bit older or just love listening loud I can imagine it can happen and then a different amp would be more suitable. Sometimes I dream of buying a second HPA4 and rigging up my XLR cables in such a way I can run them both in a balanced dual mono configuration

 

[maro65]

ah yes, with Susvara it has about 1.5W which you can reach with a bass shelf and/or very high volume (at 1.5W it produces 115db). I listen fairly low volume, I once tried to see if I could get it to clip but for me the sound got above the pain threshold before clipping occured. If you are a bit older or just love listening loud I can imagine it can happen and then a different amp would be more suitable.

Ahah actually I'm sixty years old so my ears are a bit worn out, for listening at medium/low volume even HPA 4 can be fine if you like very technical and detailed listening

 

[rlawry]

The HPA4 drove my Kennerton Rognir Planars, Dan Clark Audio Stealth, and even my Raal SR-1b ribbons wirh ease, the last phones the hardest to drive at a volume setting of about -20 dB. At that point the amp still had 35 dB of headroom remaining.

 

[w0000t]

Technologically the HPA 4 is one of the best amplifiers on the market and a reference on certain parameters, but with headphones like Susvara and 1266 with some tracks with high bass content and at high volume it went into clipping, it is true that these are borderline cases but it bothers me, the Ferrum Oor is better but still insufficient to have the best performance with Susvara and similar, even Holo Bliss is at the limit, but speaking of the DZ probably all of these can be fine

This gives me pause. I hadn't realized HPA4 might be lacking sufficient power to drive my Diana DZ which derives from the 1266..

 

[maro65]

This gives me pause. I hadn't realized HPA4 might be lacking sufficient power to drive my Diana DZ which derives from the 1266..

It's all very subjective, I like to have a lot of space for the volume, ideally at 12 o'clock I want to have a volume already quite high close to my listening volume, but if I want there must still be a lot of power available (to give you an idea it's like driving a very powerful car, you can go slowly but if you want to speed you have everything you need)

 

[plumpudding2]

This gives me pause. I hadn't realized HPA4 might be lacking sufficient power to drive my Diana DZ which derives from the 1266..

If these specs are correct the DZ is 10 db/Mw more sensitive than Susvara, and also has 20% less impedance so you'll be able to push it about 12 times louder than Susvara, which is for my 30 year old ears not underpowered or clipping the HPA4.
I don't know your hearing sensitivity or your listening habits but I think you will be fine with the DZ.