Wanted to write some formal review thoughts. I have some time to play with this amp today.
About me: I’m not in a position to spend more than about $500 on a piece of equipment. Yet. Maybe when I get rid of some stuff and save up. “Why don’t you save up for…” I dunno. It’s a lot easier to justify to myself and my wife that I didn’t spend x on a single thing. I made an exception for the Bifrost 2 because of what it is. Also covid hobbies are a thing since I’m never leaving the house ever again. Remember concerts? Those were fun. Building things keeps me busy.
Cost: $99 for the pcb, less than $200 for parts from mouser, $200 for the custom chassis.
The HP-2 has balanced and single-ended inputs. Only single ended outputs. Low (+5db) and high (+15db) gain option can be switched using jumpers on the board. All listening impressions are on low gain. That’s more than enough to be too loud on the 6xx.
I do not have an opamp based amp to compare this to. I do have an iFi Zen and Hip Dac, but those are combo devices. I have a lot of Schiit gear and this is my 2nd DIY project that I’ve finished.
I don’t know what a “high end” Topping amp sounds like, and I don’t want to know. I had a Topping NX4 and sold it. I had a Heresy and sold it. I have other solid state amps to compare, but they are all discrete circuit. The HP-2 is an opamp based circuit. The recommendation is to use OPA1656, but those were out of stock at the time I built this so I have used the OPA1612.
Chain: Bifrost 2 → balanced cables → HP-2 → 6xx or Ananda
I don’t know what a “reference” amp would sound like, but this is the closest I have experienced to what I would think that sounds like. Little to no coloration, highlighting the music and every detail possible, but remaining musical. If you don’t want a tube sound, this is an excellent implementation.
- The HP-2 is a detail monster. I feel like I’m hearing small details that I did not pick up on when using the Lyr 3, Asgard 3, or Vali 2+. I feel like I may be imaging things but every time I’ve said that someone on the forum has said, “No, I hear that too.”
- The HP-2 is clean without crossing the line into clinical. It is not rough around the edges. The Heresy and NX4 were…kind of boring or even rough. Clinical to a fault. Harsh. My BTR5 isn’t my favorite probably for the same reasons. However, I do like the iFi products, probably because of the color the Burr Brown DAC gives the music. There is no harshness on the HP-2. It attempts to be neutral and clean and I think it succeeds. The HP-2 doesn’t alter the music, it lets the music shine through. I felt the other opamp designs I’ve heard needed some color in the chain. This lets the DAC and the headphones do their job. What I have learned is that even opamp implementation matters.
- Sounds really damn good with the HD6xx
- If you are pinching pennies, you can probably order a custom chassis elsewhere for less. All of the components on the back of the chassis are connected to the PCB. There are only 3 that are wired and one uses a ribbon (which is genius and fantastic). Knowing that, it would be easy to measure holes for the back of a chassis and customize the front to your liking.
- Build time is straightforward, but stuffing the PCB may take longer than other projects. There are a shit ton of components. 70 resistors I think?
Why you want this: You want a really powerful clean amp that doesn’t add color but doesn’t detract from the music. You want an amp that highlights every detail and gets out of the way.
Why you don’t: You don’t like building things, that’s scary. You want the amp to color the music (tube, Asgard 2, etc.). You think all opamp amps are created equal (listening to this has me questioning this assumption - that most opamp amps are created equal but some may not be).
Value: From what I’ve seen on the market, under $400 (assuming you order your own custom chassis) for an amp like this is a very good value.