This message is mainly meant for Peterayer, who wanted to hear how the Pass XP-10 and the H2O Audio Fire preamps compare in my system. I am running them into a Pass X250.5 which drives Avalon Opus speakers, with a Wavelength Cosecant V3 as a source.
As I'll explain below, Unlike Muralman1 I don't think that there is a clear winner in all categories, but after listening for a week my overall preference from a listening perspective leans towards the H2O Audio Fire.
Both the Pass XP 10 and the H2O Fire preamps are fairly similar sounding when run with their single ended connections, and less similar sounding when the Pass is run with its balanced connections to a balanced amp. The Pass allows adjustable gain of either zero or ten dB. I did all my listening at the 0 dB setting because it sounded better with my source. I could happily live with either preamp for different reasons, and I imagine that a person's preference between the two would ultimately depend on the nature of the rest of their system. Until I auditioned the Fire, I had never found a solid state preamp that I would choose to listen to over a tube preamp. I can also happily listen to the Pass, however there are some quantifiable differences between the two preamps that I'll point out.
1) When running with balanced connections to the Pass X250.5, the XP-10 becomes the quietest preamp I've ever heard. With the balanced connections, the Pass preamp allows more low level background detail to come through, which aids in imaging and sound stage depth. However, at the same time the balanced connections bring forth slightly drier bass, and the overall presentation is a bit thinner than both the Fire and the XP-10 running single ended connections. The balanced connection between the Pass amp and preamp aids in making sense of densely presented music, such as classical piano or symphonic music. The XP 10 via balanced connections also bring forth the least amount of added distortion I've ever heard coming from a preamp. On certain types of music the lack of distortion can be addictive, particularly piano and female vocals. However, the quieter, drier, slightly thinner sound is not universally welcoming on all types of music.
2) The Fire presents greater micro-dynamics than the Pass XP 10. I level matched both preamps to within 0.2 dB, and the small dynamic volume shifts jump out more with the Fire with no increase in harshness. This is particulalry noticable in well recorded jazz percussion. Ride cymbal patterns show more dynamic shadings and dynamic drum whacks pop out more through the Fire.
3) The Fire has a slightly more realistic sounding treble region. The Fire, in fact, has the best treble that I've heard from any preamp. The microdynamic capabilities of the Fire and the sweet high frequencies allow beautiful detail and shimmer to come through from instruments such as acoustic / electric guitar, well recorded piano, and cymbals. However, when the frequency range drops down a bit into the upper midrange, I think the cleanliness of the Pass XP-10 presents female vocals better. When listening to specific higher frequencies of female vocals, it is relatively easy to hear that the XP-10 produces a cleaner signal than the Fire, and in these highly specific frequencies the cleaner signal is easier to listen to.
4) The Fire has a slightly warmer overall characteristic (especially if the Pass is run with balanced connections). Both preamps go very deep in the bass with plenty of control, but the midbass and midrange of the Fire is a bit more dense. How this relates to overall preference between the two preamps depends on the particular recording I am listening to. The slightly drier bass of the Pass will present more pitch definition on some bass heavy recordings, however the pitch definition can come at the expense of a slight loss of richness.
5) While both preamps do not sound at all like the typical solid state preamps I've listened to, I think the Fire has an overall slightly "sweeter" sound that results from its high frequency performance, slightly fuller presentation and increased micro-dynamics capabilities. I don't want to say that the Fire sounds more tube-like than the Pass, because the designer of the Fire might take offense at my choice of words, but hey, the Fire sounds more tube-like than the Pass. For the reasons I've pointed out above, I think the Fire can sound a bit more musical on a wider variety of recordings. However, my spouse disagrees with me. She likes the Pass better because the cleaner signal allows vocals to be more easily understood.
6) The Pass XP 10 has more features and better usability than the Fire. The Pass has an adjustable gain of 0 dB or 10 dB. The Pass has a beautiful full featured aluminum remote control that allows very fine control over the volume range, as well as the ability to directly switch to any input. The Pass has a balance control and a home theater pass through if you have needs for such. The Pass also has both balanced and single ended connection capabilities. The Fire has a remote control with volume swings that are, in my opinion, too large for the overall gain of the preamp when listening at low to medium volume levels. The remote on the Fire does not allow switching of inputs. The Fire can not be run without the remote because when the Fire is first turned on the circuit is automatically muted, and the only way to un-mute is via the remote. So, on a user functionality basis I think the Pass readily destroys the Fire.
7) Both preamps appear to be extremely well built. While the XP-10 costs five percent more than the Fire, the Fire offers an extremely robust external power supply, is hand built in the United States, and frankly offers quite a bit more physical product for the money. However, I think the luxurious usability of the Pass offers much in a different type of value.
In summary, I like both preamps for different reasons. The Fire gives more richness to the sound, and has the most beautiful, natural sounding treble I've ever heard from any preamp. Also, the micro dynamic capabilities of the Fire can really draw me in to recordings that aren't overly compressed. However, in some types of music the extremely clean sound of the Pass, when run with balanced connections, can be quite addictive and allow for easier following of dense musical passages. Also, the quieter sound of the Pass allows for better imaging in width, depth and height if your speakers do this kind of thing. Ergonomically, the Pass is a pleasure to use.
Alan
