Monoprice Liquid Gold X Review and Measurements.

I had considered adding my two cents to this thread here, but decided otherwise because I ended up writing a bit more than expected. Please go here to get a wider variety of impressions: https://www.superbestaudiofriends.o...mplifier-from-monoprice-by-alex-cavalli.8287/. I will provide measurements later. I will begin this review as a response to @songmic:

I don't have Code-X, or HE5, HE6 in the house. However, my sense is that the Monoprice Liquid Gold X would be a poor match with the HFMs. Allow me to explain.

1. The OG Liquid Gold was laid-back, forgiving, sometimes to a fault. This did wonders with the Code-X or most HFMs because they were always a bit uneven or had odd timbre in the upper mids and lower treble.
2. The Monoprice Liquid Gold X does have some semblance to the OG Liquid Gold, the heft, the dynamics, but it's actually the reverse in its treatment of the upper mids. It's lost some of the OG Liquid Gold's super refinement. However, I happen to think this works especially well with Audezes, which are the opposite in presentation with respect to HFM from the mids on up. I can also see other planars like the Final being a synergistic match with the Monoprice Liquid Gold X (LAuX) as well.

Now let's first get a few things out of the way:

1. When it comes to traditional dynamic headphones, Sennheisers, Grados, Focal, the LAuX sounds utterly disgusting. I don't know why. It sounds horrible.
2. The included DAC is a colossal piece of shit. I don't know Monoprice insisted on this. I would love to pretend that it doesn't exist, except Monoprice put a darn button labeled D and I (for input selection) on the front panel. I highly recommend the use of R2R DACs, especially the bolder or organic sounding ones for best synergy. This last bit is crucial.
3. The volume knob has a micro-penis quality feel to it. All the buttons feel like shit. I prefer gripping huge weighty knobs.
4. Do not press the gain select switch with headphones plugged into it. Pop/zap pop/zap. Someone at Monoprice should have been shot for this oversight.

For Audezes, even modded ones made to sound more neutral, there's a weird synergistic thing going on with the LAuX that goes beyond the simplistic mix bright gear with dark gear. This murky bass quality I got with dynamics transforms into textured succulent gripped articulate punchy lows with Audezes. The feeling of excessive body with Audezes, the outer qualities are addressed, while the inner warm is retained. Any fuckery in the highs in Audezes (oh yes, they are there, but just depressed), from oversharped transients, local peaks, is smoothed over without a significant negative impact in other areas. Ultimately while the LAuX isn't the last word in resolution, there's a lot of good stuff going on. By good stuff, it comes down to what matters most to me: does the system speak to me emotionally? And oh my it does. (FWIW, I'm using a MMB DAC with OPA2156 hack).

I feel like the LAuX is the cost-efficient solid-state version of the EC Studio B with WE 300B tubes. Their overall presentations are actually very similar. The LAuX has less outright outer warmth, but just as much inner warmth. The Studio B is just a nick brighter, and is less smoothed over, but that's OK because tubes. Studio B has way more expansive headstage, no surprise here. LAuX does this wide "wall-of-sound" thing, which is actually kind of neat.

I'm scratching my head why this LAuX works with Audezes, modded or otherwise, but it just does. It's the same with the Grado RS1X and iFi Go Blu, or Night Blues Mini and Elex. Component synergy is weird and unexpected sometimes.

 

Monoprice Liquid Gold X
1kHz sine
~0dBu or 0.775Vrms into 300-ohms
(2Vrms input, output adjusted via pot)
BAL in and BAL out, Low Gain


Monoprice Liquid Gold X
1kHz sine
-10dBu into 300-ohms
(2Vrms input, output adjusted via pot)
BAL in and BAL out, Low Gain


You guys get the idea. Nada with 300-ohm loads. Let's try 33-ohms next:


Monoprice Liquid Gold X
1kHz sine
0dBu into 33-ohms
(2Vrms input, output adjusted via pot)
BAL in and BAL out, Low Gain


Monoprice Liquid Gold X
1kHz sine
-10dBu into 33-ohms
(2Vrms input, output adjusted via pot)
BAL in and BAL out, Low Gain


Some third-order at higher 0dBu output level (enough to drive LCD-X to ~100db SPL), but nada when dropped down to -10dbU.

 

Monoprice Liquid Gold X
1kHz sine
THD (no N) vs. Measured Output Level
BAL in and BAL out, Low Gain


1%THD is -40db, this is where power is usually measured. The LAuX is hitting 10V not anywhere close to 1% THD yet!

 

Monoprice Liquid Gold X
THD (no N) vs. Frequency
BAL in and BAL out, Low Gain
300-ohm Load, 90kHz bandwidth


Monoprice Liquid Gold X
THD (no N) vs. Frequency
BAL in and BAL out, Low Gain
33-ohm Load, 90kHz bandwidth


With a tougher load and cranking it up, the distortion characteristic seems to affect the higher frequencies more. It's really elementary because no one is is going to run 2.45Vrms (+10dBu) into a headphone; well unless it's an OG HE-6.