Benchmark HPA4 Headphone / Line Amplifier Impressions

[rlawry]

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.

Yes, my RAAL SR-1b with its transformer interface has a sensitivity of 91 dB/mW, so very similar to the DZ. The BM should drive those to quite loud levels, something like 127 dB peaks which is jet airline engine loud.

EDIT: I thought I would post my calculations of amplifier output levels versus volume control settings.

Since the volume control range is -112.5 to +15 dB and each doubling of amplifier increases volume by 3 dB, I calculated the output power versus volume control setting into a 16 ohm load (the amp outputs a maximum of 6W into 16 ohms.)

Volume Control Setting Output Power (16 ohms)
-21 dB 0.0015W
-18 dB 0.003 W
-15 dB 0.006 W
-12 dB 0.012 W
-9 dB 0.024 W
-6 dB 0.048 W
-3 dB 0.094 W
0 dB 0.188 W
+3 dB 0.375 W
+6 dB 0.75 W
+9 dB 1.5 W
+12 dB 3 W
+15 dB 6 W

For volume control settings below -21 dB the output power is less than 1 mW so I didn't include them but you get the idea.

If your headphone load is 32 ohms and since the HPA4 outputs about 3.5W into 32 ohms, the power output at each volume control setting is about half of each figure above.

So if your headphones' sensitivity is 92 dB peaks at 1 mW of amplifier power, they will output 102 dB at 10 mW, 112 db at 100 mW, and 122 dB at 1W, the last of which is deafeningly high and will probably lead to ear damage.

 

[plumpudding2]

Yes, my RAAL SR-1b with its transformer interface has a sensitivity of 91 dB/mW, so very similar to the DZ. The BM should drive those to quite loud levels, something like 127 dB peaks which is jet airline engine loud.

EDIT: I thought I would post my calculations of amplifier output levels versus volume control settings.

Since the volume control range is -112.5 to +15 dB and each doubling of amplifier increases volume by 3 dB, I calculated the output power versus volume control setting into a 16 ohm load (the amp outputs a maximum of 6W into 16 ohms.)

Volume Control Setting Output Power (16 ohms)
-21 dB 0.0015W
-18 dB 0.003 W
-15 dB 0.006 W
-12 dB 0.012 W
-9 dB 0.024 W
-6 dB 0.048 W
-3 dB 0.094 W
0 dB 0.188 W
+3 dB 0.375 W
+6 dB 0.75 W
+9 dB 1.5 W
+12 dB 3 W
+15 dB 6 W

For volume control settings below -21 dB the output power is less than 1 mW so I didn't include them but you get the idea.

If your headphone load is 32 ohms and since the HPA4 outputs about 3.5W into 32 ohms, the power output at each volume control setting is about half of each figure above.

So if your headphones' sensitivity is 92 dB peaks at 1 mW of amplifier power, they will output 102 dB at 10 mW, 112 db at 100 mW, and 122 dB at 1W, the last of which is deafeningly high and will probably lead to ear damage.

I'm missing your dac voltage in this calculation? The output db is the gain level, so if you have a 2V input at 15db gain you get ~11,3V output voltage, which at 16 ohms would translate to 11,3/16 ~ 0,7A which would already be about 7,5W so the amp would clip.

 

[maro65]

Many times practical tests work much better than measurements on paper, there are many amplifiers such as the Ferrum Oor, Holo Bliss, Benchmark HPA4, Violectric DHA V 590/550 that as technical characteristics should drive the Susvara at its best but in reality this is not the case, they work very well but we are not at 100% of the performance that this headphone can reach

 

[rlawry]

I'm missing your dac voltage in this calculation? The output db is the gain level, so if you have a 2V input at 15db gain you get ~11,3V output voltage, which at 16 ohms would translate to 11,3/16 ~ 0,7A which would already be about 7,5W so the amp would clip.

Correct. My calculations only apply to how the HPA4 affects the signal above some reference level. In your case if the DAC output 4V instead of the standard 2V, the amp would reach its maximum output level 3 dB earlier than with the 2V input.

 

[M700LTR]

While I've not owned the HPA4, I've listened to it plenty of times at shows and shops. It drives the Tungsten DS with no issues. That being said, it felt lacking when driving the Susvara. As to the AHB2, I don't get what all the fuss is all about. I've owned 3 AHB2s at the same time with the Susvara and LCD5. I did not perceive any sonic benefits of monoblocking. I prefer the HPA4 to the AHB2, though this goes against popular opinion in Susvara circles that AHB2 > HPA4.

Lastly, the Formula S + Powerman is a good pairing for the 1266TC. I'd compare it favourably to the WA33 - 1266TC, but slightly below. I didn't find it a particularly great pairing with the Stellia, VO, Diana TC, though. I would've purchased it, but when I went to listen the 2nd time there was some buzzing sounds after connecting the Powerman.

 

[NeudorfDani41]

Really intrigued by this.

 

[w0000t]

A super generous fellow Head-Fi member who lives nearby let me borrow his HPA4 to try out—and wow, I had no idea what I was in for.

Now, I have to admit, I’m a total newbie in the world of audiophilia. I don’t have a deep technical understanding of amps, DACs, etc. Sure, I’ve got an engineering background, but mostly, I just love music. And up until now, my Diana DZ with portable amps has been pure bliss.

But last night, I plugged my headphones into the HPA4 for the first time… and my brain short-circuited. I was absolutely floored. The detail, the depth, the inky black background—it was like stepping into another dimension. Literal goosebumps. For minutes.

**Tl;dr:** Why did I wait this long to get a proper desktop amp? No idea. But now that I’ve experienced the HPA4, there’s no going back. I’m buying it.

 

[maro65]

A super generous fellow Head-Fi member who lives nearby let me borrow his HPA4 to try out—and wow, I had no idea what I was in for.

Now, I have to admit, I’m a total newbie in the world of audiophilia. I don’t have a deep technical understanding of amps, DACs, etc. Sure, I’ve got an engineering background, but mostly, I just love music. And up until now, my Diana DZ with portable amps has been pure bliss.

But last night, I plugged my headphones into the HPA4 for the first time… and my brain short-circuited. I was absolutely floored. The detail, the depth, the inky black background—it was like stepping into another dimension. Literal goosebumps. For minutes.

**Tl;dr:** Why did I wait this long to get a proper desktop amp? No idea. But now that I’ve experienced the HPA4, there’s no going back. I’m buying it.

Great buy, absolutely black background and super detail some of the strong points of the HPA4, all Diana headphones sound decidedly better with desktop amplification

 

[plumpudding2]

A super generous fellow Head-Fi member who lives nearby let me borrow his HPA4 to try out—and wow, I had no idea what I was in for.

Now, I have to admit, I’m a total newbie in the world of audiophilia. I don’t have a deep technical understanding of amps, DACs, etc. Sure, I’ve got an engineering background, but mostly, I just love music. And up until now, my Diana DZ with portable amps has been pure bliss.

But last night, I plugged my headphones into the HPA4 for the first time… and my brain short-circuited. I was absolutely floored. The detail, the depth, the inky black background—it was like stepping into another dimension. Literal goosebumps. For minutes.

**Tl;dr:** Why did I wait this long to get a proper desktop amp? No idea. But now that I’ve experienced the HPA4, there’s no going back. I’m buying it.

Love this! I had the exact same feeling first time I plugged in my headphones into the HPA4. Hope it brings you much enjoyment