RAAL-requisite HSA-1a - True Ribbon Headphone & Speaker Amp - Official Thread

These dip switches are internal so one would have to lift the lid to adjust them?

1 Like

Internal, you have to unscrew the unit and open it up! Unnecessarily painful imo but it’s a one-and-done thing, once you set your preferred input sensitivity you’re done for good unless you change the upstream gear and feel like tweaking the input sensitivity.

1 Like

Now to look into obtaining one, I’ve exchanged a few e-mails with Danny this past summer, I’ll check in with him.

Thank you.

1 Like

I’ll be curious to hear your thoughts on the performance of the non ribbon headphone output once you have enough time on ears.

Potentially interesting endgame amp if you are a SS aficionado.

1 Like

Based on my experience so far, it could be my endgame ss amp for hard to drive and not so sensitive cans given the overall flexibility of the amp - ribbon + conventional cans + speakers. However for Utopia and Stellia, the noise floor is audible through those cans and I can’t listen to them with that noise - I’ve severe aversion to amp noise. It could be because my unit is part of the first batch and the noise floor could be further improved down the line but for now, I’ll still rely on my trusty Phonitor X, Dave and TT2 HP Output.

Please note that the conventional HP output could be further improved in terms of overall refinement, resolution and detail retrieval but to my ears, it’s MUCH better than the first iteration. Having a clean upstream chain offsets those small shortcomings.


That’s unfortunate and something I have little tolerance for either but good to know. Perhaps your thoughts re future improvements will come to pass and this will improve.

1 Like

While I have been blissfully oblivious to the on-goings of the greater headphone/personal-audio world recently, I did receive my HSA-1b about 6 weeks ago. In between other stuff, I’ve gotten a review written (just need to do proper pictures … so probably published Monday or Tuesday … and also probably the last one I’ll ever do) …

I already loved the thing with the SR1a, but this is a definite improvement with conventional headphones.

Noise floor on my unit (with 0 dB input attenuation) is inaudible with every conventional headphone (even closed-back) I’ve tried it with even in a <30 dB ambient environment (and always was with the SR1a), even at max volume*, including the Utopia, Stellia and other more sensitive/lower impedance cans.

I wouldn’t run it with IEMs, but that’s a different issue anyway.

*Don’t try to evaluate this with unconnected inputs as you will get audible noise. With inputs shorted or connected to a proper source, I had no audible noise-floor with any of the headphones I tried the unit with, including my full collection per here).


Any chance for a review? I’m trying to decide between the JotR and this and have been looking forward to your review.

Either way, thank you so much for all the info and reviews you have posted on these forums. They have helped me learn a lot of about headphones in a relatively compressed fashion and I really appreciate it.


As soon as I finish processing the pictures, I’ll be posting a review of the HSA-1b. Might be later today. More likely sometime tomorrow.


w00t w00t…that’s going to be our Xmas gift directly from the Dunmore stable!


I do not have the time for a review now but I received my HSA-1b yesterday and have been putting it through the paces …in a nutshell the jotr is a good alternative for a modest sum of money…the HSA-1B is in another league…far more refined, larger soundstage…more detailed if that is even possible…simply a far better amp in every way…the Jotr is perhaps a bit more powerful but sounds almost shrill in comparison…the HSA-1B also does a nice job of driving the susvara and abyss TC using the included adapter…in a hobby where improvements are incremental I have to say the improvement here is pretty dramatic and if one can swing the cash well worth it IMHO


Adapter? Single ended to 4 pin connector?

yes, an adapter that lets you use your balanced cables out of the higher powered sr1a section with HP’s like the susvara and abyss and it works quite well

1 Like

… and … I’m only just getting to processing/editing my pictures, so it’ll probably be tomorrow, now, before I get things posted.

Any complaints about delays should be submitted on $100 bills and must be written in crayon.


:rofl: Good to know, looking forward.

1 Like

CORRECT !!! Only paying customers have justifiable expectations on delivery timetables.


I’ll put away my Monolopy money and permanent markers then…



I got the pictures edited.

Just waiting on confirmation for one new thing I want to include, and then it’ll be posted.

Which means it’ll just miss 2020 and have the distinction of being my first, and almost certainly only, review of 2021 (brief, stream-of-conciousness, impressions may be an exception).


And … I finally got the HSA-1b review posted - which I did in a dedicated thread, since the HSA-1a is no longer sold, and the HSA-1b differs enough it is a distinct product.

You can find it here.


Epic. Thank you.

[filler to get to required 20 characters for valid reply.]