If you don't enjoy my long-winded tales, and want to "cut to the chase" please skip to the last two or three paragraphs - the first three or four paragraphs are about my adventures with the unreliable electric power systems and their effects on electronics gear here in Panama.
I've had some interesting "electrical adventures" here as a retired American expat who lives in Boquete, a small town in a cool, beautiful valley at 3,200' elevation in the mountains of Western, Panama. Panama relies on hydro for 60% of its electricity, with bunker oil taking care of most of the rest, and renewables slowly remping up. The local electrical service - via "Fenosa" - is nominally 120v/60Hz - and is very flaky. Voltage runs between 122 and 128 per my DVM, and surges and sags, and outages from flickering up to several several hours without power, are fairly frequent. I have two surge protector/UPS/battery backup units, one for my mini-tower personal computer and accessories in my spare bedroom/office, and another in the living room / kitchen where my 40" LCD TV and main stereo system reside. (Related to my AC mains power, there is one weird computer glitch. When I use my microwave oven, Daphile running on an Intel NUC PC - connected to mains via AVR, UPS and surge protection - usually hangs, and I have to hard-reboot the NUC.)
Also, at my last rental casa here in Boquete, lightning hit the utility pole next door at the street - right in front of my eyes. I lost some electronics - including my $200 APC UPS, ISP/cable company modem, wireless router and Synology NAS (but not its hard drive), and later my $600 Teac AH-01 DAC/IcePower AMP. The strike also took out the house's 60A main circuit breaker out front. My neighbor, a Panamanian handyman/electrician sent me down to the local hardware store for a new one, which he replaced for free while shielding himself from the light rain a with sheet of cardboard over his head -he worked on the live 240v mains outdoors in the rain!
Recently, at my current location a couple of klicks down the road, a crew from the local utility did some work on the power lines next to our property. It was a Friday, and they left at about 5PM. Almost immediately our powerful and gusty dry season winds (which are relentless from early December into or through March) caused the newly strung wires to swing and touch, creating showers of sparks and hundreds of flickering episodes (sags and surges), eventually taking ouf one side of the 240V mains, leaving half of our circuits off, and the other still with frequent flickering and surges. It took them two days to come out and fix things. And a couple of weeks later, my Topping PA3 amplifier simply stopped working. Related? Possibly - in spite of my protection and AVR devices.
So that disabled my primary audio system, a set of relatively inexpensive components. My sources are music files on a Synology NAS or internet radio which are managed via the Daphile headless software on an Intel NUC PC. Toslink optcal connects the NUC to an SMSL Sanskrit 6th DAC, which uses RCA connects to a Topping PA3 amp, driving a pair of Paradigm Atom V6 bookshelf speakers. It's a good little system, and had been working fine, but one day, the PA3 simply stopped working. I tried to open the PA3 case to look for a fuse, but the external screws did not release the front of back plates, so I set it aside for now. I broke out my reserve - an SMSL Q5 Pro DAC/Amp, which is a popular competitor to the Topping MX3, which is the subject of this thread - until I could fix or relace the Topping PA3. (I also own Lepai and Trends Audio 12v, 15w T-amps, the 10 y/o Trends Audio amp being vastly superior in construction and components, but both have way lower power ratings compared to my Topping or SMSL units.)
So I looked on Amazon, and low and behold, there was a "used, very good" black PA3 available for $65, so I bought it. It arrived yesterday, and looked like new. I immediately put it into service with the SMSL Sanskrit 6th DAC to replace the SMSL Q5 DAC/amp and was back to my preferred system.
Most of you here who have read my comments and posts know that I have been playing with hifi audio since my high school days in the late 1950s, and have owned a wide variety of SS and tube gear in the low-to-mid price categories. I am a "science guy" and aware that subjective audiophilia is a paradise for marketers but a wasteland of idiocy to objectivists. Rather than attempting to analyze my stereo systems by focused "critical listening" I prefer to just enjoy the music.
My favorite internet radio station is a mid-fi 64kbps CBR AAC non-commercial jazz station located in Northern California, my former region of residence. It is called "The Jazz Groove," and they play mellow and mostly melodic jazz, old and new, and their playlists include a fair amount ot guitar/Hammond B3 organ tunes, which I like very much. (But they are definitely "real jazz" and not in a Kenny G style "smooth jazz" genre.)
And that brings me to my main point. The most important aspect of bass reproduction for me is the sound of an acoustic double bass of classical music origins. In spite of the limited bass response of my Paradigm Atom monitors, acoustic jazz bass on my system sounds decent, with good fullness and body. When the SMSL Q5 Pro was in the system replacing the separates - SMSL DAC and Topping amp - I would peridocally notice that the music did not sound clear and well-defined, and the mid-bass sounded congested or boomy. I found that sound irritating.
Then, after receiving the replacement PA3 and a couple of hours of casual listening to the same jazz station on the same system in the same location with my separate components (SMSL Sanskrit 6th DAC and Topping PA3 amp), I realized that the bloated mid-bass was gone, and the music sounded clear and well-defined. Subjective? Yes. But after reading this review and the posts following it, I think that my perceptions might have some merit.
(But don't hold your breath - I'm not going to obsessively perform blind testing - but rather just enjoy the music and ponder the possibilities. )