@lloyd1969 The LA4 and HPA4 sound identical. I have owned the HPA4 2x and the LA4 once. I love the lack of sound of each one.
I did not need to get the HPA4 since I had the LA4, but I was able to do a cashless trade for my AHB2 amp. The reason to get the HPA4 is as a supplementary headphone amp for what maybe the world's best headphone.
RAAL 1995 headphones, Magna and Immanis | Headphone Reviews and Discussion - Head-Fi.org
I have decided to get the RAAL 1995 Immanis and I think the HPA4 will be a nice match for the slightly warm Immanis. The Immanis is incredible. I heard it in Ventura, CA at the USA partner, RAAL Requisite. Danny McKinney is the guy in Ventura that can demo the phones. Stereophile and TAS are both going to have reviews of the Immanis.
I mention Danny because when I went to demo the 2 phones, I took my Holo Audio Serene preamp. It measures even better than the HPA4/LA4 and it a touch warmer. Danny had a passive preamp that he had put together for a speaker that he was designing. I compared my Serene to his passive and the passive was a lot better, in the sense of hearing more into the music.
I am thinking that the passive maybe even better than the HPA4. I told him that if he ever builds a passive preamp with multiple source inputs (XLR, RCA) then I would want to get one.
I actually have 3 preamps and 2 systems,
- Benchmark HPA4 with CODA #16
- Holo Audio Serene with Magenpan LRS+
- Schitt Mjolnir V3 with CODA #16
The Mjolnir v3 costs $1300 and is a pure Class A preamp. It is a headphone amp and a preamp. It is similar to the CODA 07x preamp. The Mjolnir does not have a remote control.
The CODA 07x preamp is another unit that may interest you since it has a tube -ish sound. I have the CODA #16 amp but liked the HPA4 and Serene over the 07x, though a lot of other people may like the 07x. I have seen the 07x on USAM for $3.2k+. I would take that over tubes since it is much easier to take care off.