Zähl HM1 - Reference Headphone Amplifier
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A very clear and very informative review. Well done!
A couple of things missing for the energy-conscious amongst us:
What is the power consumption at idle, and how long is the warm-up time before it comes on song?
Energy consumption is about 50W so it is something to be aware of.
Warmup time I'm actually not sure. I leave it on pretty much permanently
Very nice video review @GoldenOne
Only thing I’m missing are a few examples for one of your last sentences about high impedance low sensitivity headphones that won’t match perfectly.
Which did you try and have in mind when saying that?
Only thing I’m missing are a few examples for one of your last sentences about high impedance low sensitivity headphones that won’t match perfectly.
Which did you try and have in mind when saying that?
Wow! Thanks @GoldenOne! It was great to place a face to the famous name. A very clear and detailed look at the HM-1. I guess I’ll need to put my deposit down for one now. Oh golly gosh! 
Nothing specific as I don't actually use any 600 ohm headphones on a regular basis. But something like a DT990 600 Ohm maybe.
It's not something that's likely to be an issue and not something I've directly experienced but just doing the maths it's something that MAYBE some people will run into.
Good stuff. Given that you have also given a rave review of the Holo Audio Bliss, I wonder which headphone amp you’ll end up keeping - HM1, Bliss or both?
Bliss review will be up on my channel shortly.
I don't know if I'll keep the Bliss, likely not as it doesn't really make sense to have both it and HM1.
It is incredibly close in SQ to HM1 though, if I didn't have an HM1 I'd 100% be buying it
Doug2507
Headphoneus Supremus
2023 sold out. Wow. Wonder how full the 2024 production que is...?
Did you listen to US5 the other night when round at Ahmeds meet? I'm assuming the Bliss that was there was yours @GoldenOne ?
Did you listen to US5 the other night when round at Ahmeds meet? I'm assuming the Bliss that was there was yours @GoldenOne ?
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Ugh this makes me even more anxious for mine to get here next month (hopefully). One reason I never even considered the Bliss is the size of it. Back when I ordered the HM1 I thought I'd be combining the HM1 with a Lina stack. That ship has sailed, but even so, I'm a fiddler. I like the idea of being able to do it in a controlled manner, and Michael's expertise inspires confidence.
Does the Bliss do as well with sensitive cans as it does with the Susvara? I understand the HM1 does, though now sure how linear the scaling is.
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@GoldenOne That's an excellent review for an exquisite product. If I'm being selfish I do miss when you'd play a few more tracks and you'd talk about what you're hearing. Always on the hunt for new music, and you've got good taste.
Yeah the Bliss actually works a bit better for really sensitive stuff/IEMs than HM1.
Not necessarily in SQ itself but just the fact that the Bliss has a gain level that adjusts dependent on volume helps to keep the noise floor ultra low when running at low volumes.
SNR at 50mV (IEM Level) is the same as a lot of the topping stuff for example, so it can pump out 12W when needed or go whisper quiet for IEMs. It's a very flexible amp in that regard
That's where a dac with a variable voltage output is handy. Still I don't expect it to be a problem with the Meze Elite. I use 2v, but I still find it a bit tricky on the Oor tbh. Adjusting gain seems to have a zoom in effect going from low gain to high gain (taller soundstage as well). There's elements I like in all positions, but you do lose slam as you go down in gain.
Variable output voltage from a DAC won't help with amp noise floor
It'll help if you have a lack of actual volume control range or are so low on a pot that you get channel imbalance but that's not an issue here
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