Reviewer: John Potis
Digital source: Pioneer DV-535 DVD player feeding the Bel Canto DAC2
Analog Source: Sota Jewel table, Sumiko Premier FT3 arm, Micro Benz MC Silver cartridge, Bryston BP-1.5 phono stage
Preamp: Herron Audio VTSP-1A
Power Amp: Art Audio Carissa, Art Audio Symphony II [for review], Herron Audio M150 & Bryston 7B-ST monoblocks
Speakers: Silverline Audio Sonata Series II, Rethm 3rds [for review], Ohm Walsh 4
Cables: JPS Labs Superconductor interconnects and speaker wire, DH Labs D-75 digital interconnect, JPS Power AC, Digital AC and Kaptovator power cords
Powerline conditioning: BPT BP-3.5 Signature, Ultra-1 Z-sleeves by Z-cable
Sundry accessories: Vibrapod Isolators and Cones
Room size: 12' by 16' with 9' ceiling, speakers set up on long wall in quasi Audio Physic orientation
Review component retail: $2,640
When we last visited the saga of the Underwood HiFi/Parts ConneXion Level-2 Music Hall Mambo integrated amplifier, our own Paul Candy summed up his review with the following:



"This literally hot'n'heavy silver champ unquestionably offers a very voluptuous and liquid midrange without so much as a hint of grain. In different contexts, these distinct qualities could well outweigh what to these ears seemed like leading-edge sluggishness and a parallel overall opacity. As always, remember that one fella's perfect warmth is another's sauna; that one writer's thrill becomes another listener's restlessness. Think of the modified Mambo in terms of 'classic tube sound' and you'll have pegged its overriding traits. Whether those are what your system needs is for you to decide."
Simply put, though Paul conceded that Underwood HiFi's modified Mambo was not without merits, in the end even the considerable heat generated from its Class A circuitry failed to warm his heart. Paul also suspected that system synergy (or a lack thereof) might partially explain why the Mambo failed to light his fire. So after Chris Johnson, the modification's author and provider, confirmed that the review unit was in perfect working order (it was), I volunteered to have a go at it. And I'm glad I did. Paul's suspicion was right on the mark.


In short order, the man in brown delivered to me the exact same unit which Paul reviewed. I have to confess to being impressed by the amplifier before I ever got it plugged into the system. At 50 lbs, the Mambo is a serious chunk of 50wpc Class A stereo integrated amplifier. But sheer heft aside, it's a very nicely put-together piece as well, with beautiful brushed aluminum everywhere you look and not one powder-coated panel to be found anywhere. The front LCD readout is safely displayed through a crystalline glass window accented with polished aluminum for a very classy look. This display not only keeps a running tab on your output volume but also displays the selected input which is controlled by the knob on the left. This source selector spins in continuously stepped fashion 'round and 'round as does the volume control - but more on that in a moment.
Around back is where the Mambo kicks up the impress-o-meter by another notch. The single pair of gold-over-brass Vampire RCAs which the mod installs as a replacement for the original main input are great, but the originals are no slouches either. Their build quality will be appreciated by anyone who has disconnected a component only to find the RCA dislodged and still in the clutches of the interconnect. And the WBT binding posts are simply superb as well. The Mambo arrived with a trick-looking power cord several notches above average but in order to compare apples to apples, I continued to use the JPS Labs Kaptovator I always use on my amplifiers.


The Kaptovator is a lot of money and a lot of power cord for a product in the Mambo's class but I wanted to hear a different amplifier, not a different power cord. Considering the fit and finish as well as the solid build quality, the Mambo completely belies its reasonable asking price. It's an impressive piece.


In the listening room, the first speakers to greet it were the Third Rethms. At 100dB efficient, I was impressed with the amplifier's relative low self noise. It wasn't exactly silent, but what was there could only be heard from about a foot away from the speaker. That's actually very good performance and considerably better than my Herron Audio VTSP-1A preamp, which can't be used with the Rethms at all and, by itself, exceeds the cost of the Mambo by over a thousand dollars. And even with the ultra high-efficiency Rethms, I had all the control over volume I needed. With my high-gain Herron, I went from no output to, with the very next click, so much output that I'd wake the upstairs family at night. The Level-2 allowed me to smoothly increase the volume of the music to exactly where I wanted it. And even at the ultra-low levels required for late night listening, the Mambo's volume control tracked with perceived perfection.
I originally volunteered my follow up services to the Mambo figuring that if the amplifier was slightly shelved off or to the darker and more laid-back side of neutrality, it might actually serve the Rethms well. After all, while the Third Rethms have multiple charms, a perfectly smooth and polite frequency response throughout the upper midrange isn't one of them. With the wrong choice of amplification, this speaker could be downright aggressive. Once powered by the Mambo, I was surprised to find that they sounded essentially the same way I had observed via my much more expensive reference tube gear, with the modified Mambo exhibiting essentially the same tonal balance as my Herron VTSP-1A/Art Audio Carissa combination.


Not to get too far into the forthcoming review of the Third Rethms, the fact of the matter remains - they don't have any bass to speak of nor do they offer the usual 20kHz treble extension. They are all about midrange presence. The Mambo held up its end of the deal with real grace. I'm not going to tell you that it had the tonal saturation of my Herron preamp working in concert with the excellent and more expensive Art Audio Carissa 845 SET amp; because it didn't. Not quite. But the differences were fairly subtle and just the type of nuance that makes more expensive gear worth the extra cost. In direct comparison, the Mambo also didn't quite have the same sense of liquidity. There was a slightly mechanical quality particularly to its upper midrange. It just didn't convey the organic fluidity of the much more expensive reference pieces. If you're thinking that this is pretty much to be expected of a powerful piece of solid-state amplification that sells for less than one third of the reference combo, I'd wholeheartedly agree.


The good news on the Mambo now is that I've already given you all the bad news. Not only did it have better synergy with my room and the Rethms than what Paul Candy experienced, I had actually had a ton of fun with it. And I was just getting started.


Though I had expected the Mambo to subdue some of the Rethms' upper midrange exuberance, it did not. On the contrary, I heard remarkably little change overall and the Rethms continued their beguilingly transparent and intimate way with the music. That told me that the Mambo's frequency response was essentially flat or perhaps just a touch to the more lively side of neutral. Rhythmically speaking, the combo produced bouncy cadences and excellent dynamics. While the Mambo couldn't quite match the tonal saturation of the Art Audio, it was hardly bleached out.