This unit was loaned to me by Kitsune HiFi for review
The Holo Bliss is a product that goes a long way towards being an ultimate ‘endgame’ amp, and whilst at just over $3000 it’s certainly not cheap, but there’s many reasons to justify that.
The bliss offers a lack of compromise in design compared to other choices. Most of the time if you’re looking at amps, you’ll find that products which perform objectively great don’t always get the best subjective feedback, especially if it’s a nested feedback opamp design. But then products with subjectively well-liked aspects such as discrete designs, particularly those with features like class A topology or linear power supplies generally tend to sacrifice objective performance.
And even if you find something in the category of a discrete class A design with great objective performance, there are often other drawbacks such as either being high power (ideal for difficult planars), or low noise (ideal for IEMs), but rarely both, or maybe having an unusually low input impedance.
The Bliss however has a LOT about it that should please just about any audio enthusiast so long as the price isn’t an objection.
The Bliss is a fully discrete, class A push-pull design, and borrows many design aspects from Holo’s preamplifier the Serene. Using a linear power supply, it features upto 12W @ 32 Ohm of power, a relay controlled volume adjustment system that also incorporates a sort of ‘hybrid’ volume control, whereby partly it does a typical resistor attenuation, but also will adjust the amplifier gain itself at various levels to optimise dynamic range for the level you’re currently outputting.
The amp features three sets of inputs, two XLR and one RCA, which you can switch between using the front controls or the remote, and also a set of XLR and RCA preamp outputs. These don’t operate simultaneously with the headphone outputs, so you can leave a speaker system connected whilst running headphones if you’re using the bliss as a preamp.
The front has two balanced outputs (XLR-4 and 4.4mm Pentaconn) and a quarter inch single ended output. The display will show the currently selected output as well as the current level of gain/attenuation in dB, which ranges between +12dB and -72dB.
The outputs can also be configured to run ‘Lo-Z’ or low output impedance, or if you have higher impedance dynamic driver headphones, you can also switch the outputs to ‘Hi-Z’ which deliberately increases output impedance. This will slightly alter the frequency response of dynamic driver headphones in a way that many people subjectively enjoy.
The featureset and IO of the bliss are comprehensive, and as you’ll see shortly, so is the performance. BUT, the main drawback is that the bliss is physically very large, and due to the high heat output, it’s suggested that you do not stack this with other hot components, so it may not be particularly desk friendly.
– Audio Precision APx555 B-Series Analyzer with 200kOhm input impedance set unless otherwise specified
– Neurochrome HP-LOAD Dummy Load
– All measurements shown are with the amplifier being fed XLR unless otherwise specified
– Measurement setup and device under test are running on regulated 230V power from a Furman SPR-16-Ei
– Audioquest Mackenzie XLR and RCA interconnects
– Exact analyzer/filter configurations for each measurement are detailed in the full reports
– Measurements shown are with the amp in ‘LO-Z’ from the XLR-4 Output unless otherwise specified
– All tests shown are using a 32 Ohm load unless otherwise specified
Full Measurement Reports:
Reports available here:
SNR (from 4V): 119.2dB
IMD SMPTE: -111dB
DC Offset: 0.9mV active, 0.1mV idle
CMRR: 67dB (same value at 100hz, 1khz, and 10khz)
1khz Sine, 4V XLR in, Amp set to 0dB, XLR Out (300 Ohm):
Excellent performance here with all harmonics below -140dB. In fact that harmonic I think actually is from the analyzer itself in large part, not the amp! The THD+N value here is mostly noise limited. What about if we change the amp to ‘HI-Z’ if we were running 300 Ohm headphones?
1khz Sine, 4V XLR in, Amp set to 0dB, XLR Out (300 Ohm, HI-Z):
Nearly identical performance, nice. Just pick which sounds best to you in terms of Hi-Z vs Lo-Z. Though be aware that on Hi-Z the max power rating is lower (2.5W @ 32 Ohm vs 12W @ 32 Ohm). So for planars you probably want to stick to LO-Z.
1khz Sine, 4V XLR in, Amp set to 0dB, XLR Out (32 Ohm):
With a difficult load distortion is a bit higher as is to be expected but still incredibly low.
1khz Sine, 4V XLR in, 700mV XLR Out (32 Ohm):
At headphone levels the amp is doing fantastic and THD+N greatly exceeds 16 bit resolution.
1khz Sine, 4V XLR in, 50mV XLR out (IEM Level, 12 Ohm):
Likely thanks to the amplifier’s ability to adjust gain down when set to lower levels, for IEMs the bliss does wonderfully, sitting alongside the lowest noise amps from topping for example, so it can comfortably run both the hardest to drive headphones and sensitive IEMs.
1khz Sine, 4V XLR in, Amp set to 0dB, XLR preamp output:
The Bliss is massively powerful, with upto 12W @ 32 Ohm (unfortunately my dummy load is only rated for 10W so I can’t go higher than that). And not only does it have an incredibly high maximum output, it also shows minimal additional distortion as the load gets more difficult. Many other ‘powerful’ amps might have dozens of times higher distortion at a couple watts even if they can technically output 6-10W.
Volume Channel Matching:
The Bliss uses relay controlled relay attenuators for volume control. Channel balance was within 0.01dB at all volume levels!
Output impedance on the bliss actually depends on both what output you’re using, and whether it’s set to Hi or Lo Z.
XLR-4 = 0.02Ω
4.4mm = 2Ω
6.35mm = 1Ω
XLR-4 = 15Ω
4.4mm = 17Ω
6.35mm = 8.5Ω
I’m not too sure why the variance in output impedance, though I presume it is likely for the purposes of short protection. 4.4mm and 6.35mm jacks can short-circuit when being plugged/unplugged whereas XLR cannot, so it’s probably just for short protection to prevent risk of damage to the amp.
However, this is a bit annoying for IEM users, as the 4.4mm output will likely be the main one they’ll want to use, and a 2Ω output impedance will be enough to alter the frequency response of many IEMs.
However, the easy workaround is just to buy an XLR 4-pin to 4.4mm adapter. These can be found pretty cheap. Just make sure that you always connect/disconnect the XLR part. Don’t plug/unplug the 4.4mm jack into the adapter whilst it’s connected to the amp.
IMD SMPTE (Intermodulation Distortion):
DIM (Dynamic Intermodulation Distortion):
THD+N vs Frequency:
Overall, the bliss performs amazingly well! Particularly the fact that you can get such massive power out of it whilst also being among the quietest amps for IEMs, combined with all other aspects of performance, this is a truly phenomenal design. Well done Jeff Zhu!