Foreword / YouTube Video Review
This item is my own. I purhased it to review. I was not paid nor given anything in return for this review.
All my reviews are done on my own time with great care to give you all the best set of data and information I can provide in order to help you make a well-informed purchase decision. I offer this for free to all who are interested. In return, if you want to support this site please see the bottom of this review for ways you can help. It is greatly appreciated.
The review on this website is a brief overview and summary of the objective performance of this processor. It is not intended to be a deep dive. Moreso, this is information for those who prefer “just the facts” and prefer to have the data without the filler. The video below has more discussion with respect to the technical merits and subjective notes.
Information and Photos
Some specs from the manufacturer are below and full specs can be found here.
- Audio Performance
- Power Output (THD = 0.08%, two channels driven): ▪ 100 W per channel @ 8Ω▪ 200 W per channel @ 4Ω
- Amplifier Technology : Class-D with PFFB (Post-Filter Feedback) technology
- Total Harmonic Distortion (THD+N): ≤0.005%, -106 dB (A-weighted)
- Signal-to-Noise Ratio (SNR) : ≥120dB
- Damping Factor: 94
- Frequency Response: 20Hz – 20kHz ± 0.5dB
- Impedence Range: 2 – 8Ω
- Audio Processing
- Premium Audio Components: ESS 9039Q2M high-performance DAC, Dual TI TPA3255 Amps, TI OPA1612 op-amps for ultra-low distortion and rich, detailed sound.
- Bit-Perfect Playback: Supports up to 192kHz/24-bit audio
- Dynamic Range: ≥120dB for high-resolution sound
As of this writeup, the MSRP is approximately $529 USD.
Review Starts Here
Overview
The WiiM Amp Ultra is the latest offering from WiiM. I imagine the next iteration will be “mega” or “super duper”. At any rate, let’s go through the data. If you’re looking for a reference amplifier to compare these results against, then I recommend my review of the McIntosh MC611 monoblock found here.
Testing Info
- Warmup: Unit was provided pink noise with an output of 1 watt into a 4-ohm load for 10 minutes.
- Test Bandwidth: 22.4kHz (48 kHz Sample Rate) (unless otherwise stated)
- Input to DUT: Unbalanced RCA.
- FFT size: 32k (128k for multitone for better LF resolution)
- Tests were run at 2, 4 and 8-ohm static loads.
- Beyond the static loads mentioned above, Reactive Loads were also used for testing and noted. Both a “simple” and “complex” load. These are designed to emulate a true speaker load without risking damaging a real speaker or deafening myself to test tones from a real speaker. The impedance sweep of these loads are provided below.
Note: Due to server space costs, results published here focus on the 4-ohm testing (unless otherwise noted). However, all the 2/4/8-Ohm data are provided on my Patreon page (Patreon link).
Frequency Response
Using both my static 2/4/8 Ohm loads in addition to my “simple” and “complex” reactive loads, I found the response is practically unchanged. There is some mild deviation due to the complex load, but it’s no more than about 0.10 dB. No one is going to hear that.
THD+N Results
-
Amp matches or exceeds the rating
-
Output at 0.10% THD+N:
- 2Ω: See Below *
- 4Ω: 200 watts per channel
- 8Ω: 100w watts per channel
- “Simple” Reactive Load: 100 watts per channel
- “Complex” Reactive Load: 200 watts per channel
-
Note: while the WiiM Amp Ultra is not rated at 2Ω I did perform testing. The results you see below show the maximum power hitting approximately 256 watts per channel before the device enterered protection mode and muted the outputs.
Max Power & Burst Power
- Continuous vs. CEA-2006 max burst @ 1kHz, 1.0% THD:
- 2Ω: 243/248 watts / * @ 1.900 Vrms Input
- 4Ω: 219/222 watts / * @ 2.176 Vrms Input
- 8Ω: 112/114 / * @ 2.180 Vrms Input
*Note: CEA-2006 Burst Testing was attempted but was not successful. There are some potential reasons why such as soft limiter or a limited power supply. Without WiiM’s input (or others’ testing) I cannot say for sure.
“Heavy Lifting” Observations
During the majority of my test, I focused on the 4-Ohm setup. So what I talk about below is with this focus in mind.
- 5w SINAD: ~87 dB (≈ 0.004420% THD+N)
- Rated Power (200w) SINAD: ~70 dB
- Dynamic range: N/A. See comments above regarding lack of CEA-2006 Burst Test Results.
- Multitone @ 5w and 200w: ~100 dB dynamic range
Frequency Response
SINAD vs Level
Crosstalk
Bench Mode Results
The following sections provide screenshots of the bench testing which uses single test tones, IMD, and Multitone test signals. The screenshots can be viewed in the following manner:
For IMD and Multitone testing note the input voltage which is intended to match the single-tone input voltage to meet a desired power output. For example, to achieve ~5 watts with a single 1kHz tone I might use 410.0 mVrms to get a reading of 5.029 watts.
Single Tone
5 watts
200 watts (rated power)
Multitone
5 watts
200 watts (rated power)
Summary
You can see my embellished thoughts regarding the WiiM Amp Ultra in the video linked above. There is a lot about this product beyond just the data you see above. However, the key focus in this written review is that the amplifier is technically a sound product. It has relatively low noise floor, produces rated power (ableit, with apparent dynamic range or burst limitations). In my opinion, the bread and butter of this product is the WiiM app which allows you a lot of nice features from streaming sources, room EQ (which is actually pretty good), 10 bands of independent left/right parametric EQ, and more. Add in great build quality and a nice look and you’ve got a solid streaming amplifier.
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