Lol this is a ‘feature’? Seems broken design.
Anyway as long as the lower OP impedance is near zero, no big deal - that’s where I’d leave it.
Yep
If you don’t like it you can just leave it off without worry.
As said, it’s something which a lot of people subjectively enjoy and so there are a lot of amps both SS and tube which have configurable output impedance.
Bliss, Singxer SA-1, Woo WA22/WA33, Feliks Envy, Cayin IHA-6 etc etc
It doesn’t have any negative impact if you choose not to use it
4 Likes
Having the option makes it very versatile. Not sure I’d want a wa33 for example without it…
2 Likes
Yeah it’s a feature I personally quite like.
HD800 I almost always use the Hi-Z option on any amp that has it for example.
2 Likes
I have the Icon Audio HP8 transformer-coupled tube amp. It has 3 impedance settings (low, medium, high). The three settings all sound the same (on headphones of various impedances), but the volume goes down w/medium vs low; and with high vs medium.
I can’t explain that…only report it.
Are you using planar headphones?
Planars have a flat impedance curve so won’t have their FR altered in the same way that dynamic driver headphones do
1 Like
Even there you can usually hear the loss of driver control as the output impedance rises. Especially given what it is on high for most tube amps.
On tube amps you also get peak power into differing impedances based on what transformer tap is selected (which is how it’s mostly done).
3 Likes
6 Likes
How close is your mic? Seems even louder than my Freya+ which has a clicky 128 relay-switched stepped attenuator. This is what it sounds like: Any colour you like with the Schiit Freya + - YouTube
Imagine in the future having the option to attenuate the volume of the volume knob lol, just how we can adjust display brightness.
Looking forward to your and others’ impressions of this amp!
Oh yeah its definitely louder than Schiit stuff.
Its quite a satisfyingly heavy ‘thack’ almost.
Some people wont like that but personally I find it really satisfying
1 Like
Very much looking forward to your review. I feel like there’s one of these in my future, but I need confirmation. lol
2 Likes
Ditto to all of this! Very interested in hearing more about this amp.
2 Likes
Curious for your report on break-in hours required for the Serene.
My Holo Spring 3 KTE took an honest 200 hours to break-in and almost 500 to fully break-in.
Not complaining, just was surprised how congested it was initially and how it opened up. Had it running with test tones and high dynamic range material for days with ROON on a loop; while checking-in each evening with a listen.
Never had a Holo DAC. But I have had 3 Audio GD DACs (R2R or NOS, no tubes in circuit) that took a legit 500 hours to finally settle down to their final sound. I read that from several users and thought they must be out of their minds–but I proved for myself that they were right on the money.
Can’t explain it/just report it…
2 Likes
I do believe that people’s perceptions of amps, DACs, and headphones changes over time, but also that this has as much to do with learning, training, or habituation as burn in. Any device that produces structured harmonics (e.g., tubes, “euphonic” tunings, etc.) is likely to be predictable through brain processes. It happens much too fast to be conscious, but there is a reliable “warmth” or “fuzz” or “edge” based on device characteristics.
Research Question: Device burn in versus human training and habituation
-
For a device to burn in there must be some change in how it operates. This might be measurable or not measurable, and certainly can happen with moving parts (e.g., headphone pads or speaker surrounds).
-
Humans hear new things and learn all the time, but the tough part of testing is that it’s a one-way street. Once you are experienced you can never go back to being a novice.
Method: Evaluating 500 hour burn in versus human learning
-
Find a group of 30-50 people who’ve never heard a Holo DAC or an Audio GD DAC or a Schiit multibit DAC, and who are not into the audio hobby at all (and compare them to experienced users; not listed below)
-
Have one group listen to a new DAC for 15 to 60 minutes per day, every day until the 500 hour mark is reached
-
Have a second group listen to a pre-burned DAC for 15 to 60 minutes per day, every day until the 500 hour mark is reached
-
Have a third group listen to a new DAC at the 1 hour mark, 250 hour mark, and 500 hour mark only
-
Have a 4th group listen to a pre-burned DAC on Day 1, Day 10 (24 hours x 10 days = 240 hours), and Day 20 (24 hours x 20 days = 480 hours).
Data Analysis: For all groups, compare ratings on perceived sound quality. Compare abilities to identify new versus burned-in DACs. If the pre-burned DAC sounds different to everyone or most people over time, then human perceptual learning has occurred. If ratings of new DACs reliably change over time (i.e., different data patterns than pre-burned DACs) then the device itself changes.
Etc.
3 Likes
I have experienced changes on both the R26 and May at the 300-500 hours through multiple sessions and varying low bass shelves from 3-4db down to .50.
With Mitch Barnett’s convolution filter, I think May has settled right at 450-500 with the last few sessions at .75db unchanged so far. Will keep burning to see if further changes happen leading to 1000 hour mark as a couple have stated but remain skeptical.
1 Like
It’s a very interesting subject for research, I have also questioned this and had my own experiences with my gear. I feel like it has been noticeable with some headphones, but much less with others.
My experience with electronics burn in has been (much) less noticeable. Differences with a tube amp (Schiit Valhalla 2) I thought were detectable, but not extreme. Same with Yggdrasil OG to be honest. With the Yggy everyone said it needed to be warmed up for “days” to sound right as well, I never noticed much difference, especially after several hours on to come to temperature. I leave it on all the time anyway… 
1 Like
@GoldenSound how about a early hot take? Enleum CFA3 or Bliss for the Susvara?
I’m actually not much of a fan of the Enleum. I have a full review coming.
CFA3 is excellent, but I prefer Bliss.
4 Likes
Nice, thanks.
Is the HM1 worth the added cost (or even half worth) over the Bliss for sound quality? If we ignore the other features it has…