[Currawong]

I have a few dynamic-driver IEMs. With the exception of Zero Red whose FR is designed to interact with the output impedance, everything else works with the current output. The improvement/change going from voltage output to current output on my E500 is quite staggering, in a good way. The imaging improves vastly and the treble is more refined, all without changing the FR. The midrange sounds completely different from what I'm used to hearing from the E500 on different setups, and I don't think the word "imaging" captures well the differences I hear. But it is a favorable change nonetheless. I posted some measurement here.

The voltage output and current output have an identical FR, so I'd say it was "compatible". The change going from Hugo2 to Hugo2+23RM voltage was a <5% improvement in soundstage, imaging and depth. But the overall presentation of the music is still the same and familiar. The change going from Hugo2+23RM voltage to Hugo2+23RM current is hard to quantify. The treble is straight up better. But the rest is almost like someone did a remastering on the recording. If you are familiar with audiophile remastering, it sounds like an AP remaster instead of a MFSL remaster. Very hard to describe... With the voltage output, the music sounds more "whole", you know, like how it is supposed to be. I hear the soundstage as outlined by the decay of instruments. With the current output, the music doesn't sound "whole" anymore; instead, I hear individual instruments playing, somewhat disconnected from each other. The decays are still audible but more localized. I "hear" less of the soundstage. Perhaps "dry" (as in reverberation) is the word I'm looking for...

Another thing to note is that I find myself listening to the current output at a higher overall volume than the voltage output. One thing I've learned from the hobby is that if a change in the chain makes me want to withstand loudness, then the change is a favorable one. So I'd say I like this current output.

That's super helpful! I thought that there might be a couple of IEMs that have a flat impedance-vs.frequency, but it's not something that is clarified much in the IEM world, as the Enlenum is something of an outlier as far as amp designs go.

Hugo 2's line out is 3Vrms, very high. At 3Vrms I can hear clipping from the 23RM, so I have to connect the Hugo 2 via pre out. I set the volume on the Hugo 2 to about 1/3 of the way (not sure what Vrms it corresponds to), set the volume on 23RM on low gain to about 11, and listen to the E500. I adjust the volume on Hugo 2 instead of the 23RM because 23RM's volume step is larger.

I recommend not using the line out mode. It's just a volume setting on the Hugo 2, as it doesn't have a separate circuit for a line out (the design is significantly different to a typical DAC). Rob Watts did post somewhere what colour corresponds to what voltage somewhere.

 

[dsyzling]

That's super helpful! I thought that there might be a couple of IEMs that have a flat impedance-vs.frequency, but it's not something that is clarified much in the IEM world, as the Enlenum is something of an outlier as far as amp designs go.

I recommend not using the line out mode. It's just a volume setting on the Hugo 2, as it doesn't have a separate circuit for a line out (the design is significantly different to a typical DAC). Rob Watts did post somewhere what colour corresponds to what voltage somewhere.

In your experience what would you recommend? I know this might be amplifier specific and I'm thinking of the 23R personally, but I guess more so in general with the Hugo 2 (and other Chord dacs). Are you suggesting setting the amp at a fixed volume/output to match headphones for example and then using the Hugo 2 volume control or adjusting the output of the Hugo 2 to match the input of the amplifier and then using the amp's volume control?

 

[Edric Li]

Thanks Edric,

Thanks. Make sense... I am figuring out how the HPA23 would fit my range of IEMs...the more efficient ones could still be a problem. How about noise?

It is less about the efficiency and more about the impedance curve, I believe.

There is no noise floor issue with the current output on the E500, but there is on the 7Hz Zero 2. You can check their sensitivity/impedance stats online, but I would describe Zero 2 as medium-sensitive and E500 as not sensitive, among all the IEMs I’ve used. So yes, I would imagine highly sensitive, multi-BA IEMs to have a high noise floor on the current output. This is assuming that their impedance curve is flat, that plugging them into the current output is meaningful to begin with.

The Zero 2 “works” with the current output, as in no weird FR (see impedance curve measurement on ASR), and benefits from it in a similar way as the E500 does, though to a lesser degree. I hear a more refined uppermids all the way up to the air frequencies, but the difference is more subtle than on the E500. I don’t think the noise floor is high enough to impact the enjoyment, so I use the current output on the Zero 2. I’ve been told my listening volume is very low, fyi

 

[Currawong]

I wonder if the old HFM R2000s would work from the current out. I might have to try that, as they are 60 Ohms and work out of regular headphone amps.

In your experience what would you recommend? I know this might be amplifier specific and I'm thinking of the 23R personally, but I guess more so in general with the Hugo 2 (and other Chord dacs). Are you suggesting setting the amp at a fixed volume/output to match headphones for example and then using the Hugo 2 volume control or adjusting the output of the Hugo 2 to match the input of the amplifier and then using the amp's volume control?

With the Hugo 2, in many cases, the internal volume control will be better than the volume pot of the amp, so it's quite reasonable to set the amp's volume to max and use the Hugo 2 to control the volume.

Maybe the biggest issue, if it can be called that, is that the Hugo 2 already has an excellent headphone amplifier, and the HPA-23RM matches that, but I don't think bests it.

 

[tassardar]

Thanks Edric,

Thanks. Make sense... I am figuring out how the HPA23 would fit my range of IEMs...the more efficient ones could still be a problem. How about noise?

The use some IEM including the relative sensitive ones (Simgot EA1000 with 127Db/Vrms). Voltage out has no issue and works pretty well with minimal noise.

Current out may have some really low humming sound depending on IEM. It's almost inaudible in normal room environment unless you focus on it and not playing music. I tried a few IEM and some works some don't with the Enleum.

 

[tassardar]

I wonder if the old HFM R2000s would work from the current out. I might have to try that, as they are 60 Ohms and work out of regular headphone amps.



With the Hugo 2, in many cases, the internal volume control will be better than the volume pot of the amp, so it's quite reasonable to set the amp's volume to max and use the Hugo 2 to control the volume.

Maybe the biggest issue, if it can be called that, is that the Hugo 2 already has an excellent headphone amplifier, and the HPA-23RM matches that, but I don't think bests it.

I think it sounds different rather than beating the Chord series. This difference especially on the current output can be noticeable and better or worst depending device. The voltage side for me it doesn't quite beat the Hugo TT for me. Slight different in sound but not better.

 

[MindsEyeKay]

Sharing a link below on enleum compatibility with headphones and its effects for the current port.

https://docs.google.com/spreadsheets/d/10NYPSk0Ne2g-CKtNhXhvs-r9urQn8ldGd_9kt0I1aE4/edit?usp=sharing

Hey @tassardar thanks for taking the time to put this together. Much appreciated.
Did you get a chance to try out the Sony MDR-Z1R with the HPA-23RM.

P.S. I posted this request on your YouTube review...

 

[tassardar]

Didn’t get to listen to it yet. Need to visit a Sony shop and not sure if they let me pull their headphone out of their amps

 

[MindsEyeKay]

Didn’t get to listen to it yet. Need to visit a Sony shop and not sure if they let me pull their headphone out of their amps

OK, no worries. No need to go through all that effort, just thought if you have easy access to a pair.
Thanks!

 

[mt-hifidelity]

Does anyone know if the PWA RCA adapter for the Hugo2 will work with the 23RM's RCA inputs?

https://www.mtmtaudio.com/products/...-to-rca-male-adapter-for-chord-hugo-amplifier

 

[weexisttocease]

I'm considering buying the 23RM and use the 320MAX as a source. Would you recommend the Hugo 2 too?

 

[Edric Li]

Does anyone know if the PWA RCA adapter for the Hugo2 will work with the 23RM's RCA inputs?

https://www.mtmtaudio.com/products/...-to-rca-male-adapter-for-chord-hugo-amplifier

It will not (although I’ve not tried). The RCA sockets on the 23RM is slightly closer to each other than on Hugo 2.

 

[czervonk]

I am not shure if I am alone with that but I prefer voltage output with my Sennheiser HD800s and DCA Expanse. For me current output is too dense in opposite to more space from voltage output.

Hello,

This is self reply but I have reasons. I discovered why I prefer voltage output. Recently I tested Woo Audio Dac Cable and I was shocked how good current output is. I experienced really big stage in the opposite to really close stage, stereo like without depth. Normally I use Questyle CMA 15 which has 2V on RCA output. Woo Audio Dac Cable has 1.7V so I tested preamp function in Questyle and when knob is on 100%(2V) I can observe described problems at lover volumes stage opens and sound is really holographic. Also whats strange on Sennheiser HD 800s I can notice audible noise on current output. I tested it also with other Questyle CM 15 and SMSL M400 in my local dealer with the same results. I suspect that my unit is invalid. I have sent it to Enleum service through my local dealer.

 

[Edric Li]

Hello,

This is self reply but I have reasons. I discovered why I prefer voltage output. Recently I tested Woo Audio Dac Cable and I was shocked how good current output is. I experienced really big stage in the opposite to really close stage, stereo like without depth. Normally I use Questyle CMA 15 which has 2V on RCA output. Woo Audio Dac Cable has 1.7V so I tested preamp function in Questyle and when knob is on 100%(2V) I can observe described problems at lover volumes stage opens and sound is really holographic. Also whats strange on Sennheiser HD 800s I can notice audible noise on current output. I tested it also with other Questyle CM 15 and SMSL M400 in my local dealer with the same results. I suspect that my unit is invalid. I have sent it to Enleum service through my local dealer.

I've noticed a slight distortion at one point too. Later I discovered that the RCA cable was the culprit. There is a distortion if the cable was a Van Damme Pro XKE cable. Every other similarly spec'd Canare/Mogami/Gotham instrument/mic cable I have was fine. This is with the DAC (Hugo 2) output at about 1Vrms. Have you tried different RCA cables at your dealer?

But I think you nailed it with the dense (current) vs space (voltage) distinction...

 

[czervonk]

I've noticed a slight distortion at one point too. Later I discovered that the RCA cable was the culprit. There is a distortion if the cable was a Van Damme Pro XKE cable. Every other similarly spec'd Canare/Mogami/Gotham instrument/mic cable I have was fine. This is with the DAC (Hugo 2) output at about 1Vrms. Have you tried different RCA cables at your dealer?

But I think you nailed it with the dense (current) vs space (voltage) distinction...

Thanks for replay. I thought about it too. Thats why I checked it with my both Livracables and Audioquest RCA cables. During test in dealers shop I used some Fiio RCA cable.