Okay, here we go: my thoughts on the comparative synergy of the DX50 with the Quickstep (or QS) and the Pico Power (or PP). This is not an amp review of the QS and PP. Firstly I don't do amp reviews; I analyze my preferences more with imagery than correct audiophile-speak. Secondly, such a review would not be appropriate for this thread.
What are the qualities of the DX50 that would make it have synergy with a specific amp?
- Firstly, the DX50 line out does not have a gain stage. The gain stage is one of the most important aspects of implementation in home DACs. Even with a portable DAC such as the VentureCraft Go-DAP DD Socket 1, people are spending hundreds of dollars extra to substitute in military spec opamps for the default gain stage options. A gain stage increases volume, allowing for a greater dynamic range and an overall fuller sound when then amplified.
- Secondly, the DX50 line out is shockingly clean, i.e. distortion free. iBasso says that THD+N is 0.003%; my ears says that this cannot be far from the truth.
- Lastly the Wolfson 8740 DAC chip in the DX50 has a slightly warm "musical" tone by comparison with, for example, the typical Cirrus Logic chip. It is certainly more musical than the very good line out of the iPod Classic with which it inevitably competes.
What are the qualities of the Quickstep and Pico Power that are relevant to their potential synergy with the DX50? I will discuss here what they have in common, leaving the differences to individual discussions below.
- Neither amp is especially small or inexpensive. Each runs off 9 volt batteries, one for the QS and two for the PP. Neither has an internal charging circuit. Instead the internal space of their respective largish cases is devoted to amp circuitry. The decision to buy either of these amps to use with the DX50 is a decision to pursue maximum sound quality from the top portable offering from two of the best designers out there, not to maximize portability and convenience.
- Both amps put out huge amounts of power, swinging enough voltage to competently drive full size cans like Sennheisers and Beyers. I am using the DX50 + amp combo exclusively with IEMs but this massive portable power is relevant, especially since the DX50 line out has no gain stage. The DX50 line out is clean and musical but it is also a bit 'thin'. The power of the QS and PP is extremely welcome, significantly thickening and improving the sound by comparison with a less powerful amp such as the circuitry which is built into the DX50 headphone out.
- Both the QS and PP have extremely low harmonic distortion. Given how clean the line out is from the DX50, pairing an amp with poor THD measurements would be more than a shame, it would verge on an outright crime.
- While the Meier Quickstep has Jan's fantastic discreet 32-step volume control, the analog volume pot of my PP has excellent channel balance well below listening levels with my most sensitive IEMs. So both have great low volume control with IEMs (which is what this post is exclusively focused on). In addition, both have output impedance < 1 ohm.
But what about the synergy of the individual amps with the DX50, huh? Any plans to get to the point? Well, okay...
In short, both of these amps sound absolutely fantastic with the DX50 but there are differences.
DX50 and Quickstep
The Quickstep has Jan Meier's active balanced ground and it is as fast as any portable amp that I have heard. Attack and decay are excellent. It also has a sound signature which is quite unique. I have put much thought into how to describe it and what I have come up with is "cool lush". It is not a warm amp but it is not strictly 'gain by wire' either. If a warm amp can be describes as akin to walking into the steamy foliage of a jungle, the QS is like walking through a borealis forest on a cool summer night. If that imagery doesn't work for you, tough, it's my post. What this means is that the sound of the QS is actually quite full but it is not adding warmth to the already slightly warm DX50 line out. With reasonably neutral-of-tone IEMs like my ES5 and Flat-4 Kaede, the results are stunning. I would describe the sound as luxurious. Yes, an amp can actually sound luxurious; legions of Meier fans know something that you don't. The QS does everything right combined with the DX50, not a harsh note in the trebles, lovely mids and solid fast bass. The one negative that I will throw out there is the combination of DX50 + QS with a colored headphone like my euphonic Final Audio Heaven VI does not produce absolutely ideal synergy. The QS + Heaven VI with a neutral DAC, and the DX50 + Heaven VI with a less lush amp can both be excellent with the right third component. The three together though, while certainly sounding very good, is nonetheless a little "rich" of sound to my tastes.
DX50 and Pico Power
If the QS sound can be described as cool lush, I would say the the operative words for the Pico Power are "boldly honest". Well, we have to be careful here. The PP has a discrete output stage using NOS transistors rather than the standard output buffers. The result is a sound that is a bit relaxed in the upper register. There is a nice organic quality to the treble. Still I use the terms "boldly honest" for the PP because it just throws so much dang power into the mix without a hint of the QS lushness. The result is a great sense of presence. The QS does not lack for transparency but the PP ups the ante. This synergizes perfectly with the thin but slightly warm line out of the DX50, even with colored IEMs like the Heaven VI. To my ear, if the QS is the more luxurious sounding of the two amps, the PP is the more honest. It has a huge sound that just sounds true to source. The other quality that distinguishes the Pico Power is the bass. The QS is no slouch in this department but for driving IEMs, the PP has the best bass that I have heard in a portable amp. It has remarkable power and impact without a hint of bloat. The DX50 line out is frankly not a bass monster and the PP's ability to resolve so much bass detail and generate so much impact with the DX50 is extremely welcome. (Note also that this is not the product of any artificial bass boost; the Inner Fidelity FR tests show that the PP is utterly neutral.)
So which should you buy of these two amps (if you happen to be asking; I don't assume that you are)? Frankly you can't go wrong with either. The main point I would make in this post is that most portable amps out there are pale shadows of a good desktop amp. Often much of the circuitry is devoted to charging and sundry extraneous features. There isn't a lot of genius between the batteries and volume pot. Both the Quickstep and Pico Power, the top of line portable offerings from the respective genius of Jan Meier and Justin Wilson, offer true desktop quality is a fairly portable if not quite diminutive package. In my view, the DX50 deserves this. The DX50 is that fine a source and an amp that is just good will not realize its full potential. In addition, the lack of a gain stage in the DX50 means that a truly powerful amp (verging on IEM overkill with the Pico Power) brings real benefit.
(And yes, there are other truly great portable amps out there but not so many as the posts in this thread would suggest...)
Frankly, with the Quickstep on sale through Christmas for $325, versus $475 for the Pico Power, it is probably the no-brainer best choice for most people. It is certainly the value choice. The combination of the DX50 and Quickstep has to be heard to be believed. The clean slightly warm output of the DX50 synergizes beautifully with the fast and clean but also cool lush sound of the Quickstep. Luxury, dudes! Put on your smoking jacket, sink back into your red leather chair and drink in the excellence. The only caveat I would put on all of this is that it is not the absolute ideal combination for a euphonic colored IEM such as my Heaven VI - not bad at all but not perfect.
Having said this, what this exercise has taught me is that I have a new favorite portable source and a new favorite portable amp. The DX50 + Pico Power is my A-rig. It is stunning. The choice of the PP over the QS would be easy since I listen to the euphonic Heaven VI often, especially on trains and in other environments where isolation is important. However even with the more neutral Kaede (and also the well-isolating and neutral ES5 for that matter), the Pico Power is still my favorite amp with the DX50. They both sound great but I prefer the slightly relaxed yet boldly honest sound of the PP over the fast cool lushness of the QS. The class-leading bass reproduction in the PP just seals the deal.
In addition, while both amps stack nicely with the DX50, I slightly prefer the ergonomics of the DX50 + Pico Power stack. The PP is a bit thinner than the QS and its larger dimensions match the DX50 almost perfectly, being just a few millimeters longer and a few millimeters narrower. It sits quite comfortably in the palm of my (admittedly large) hand.
To be clear, my highly personal and unashamedly subjective imagery above is operating on a fairly subtle level. These two amp are both frequency neutral, uber-clean power behemoths that sound more alike than different. But in the subtleties, the differences are real. I have no intention of selling the Quickstep. It is technological marvel and a gorgeous performer. When I want that lusher sound - and sometimes I do - swapping amps is just an elastic snap away. But as my daily choice for portable and transportable listening, this beauty has won out:
Ummm... YMMV. Did I have to say it? :-)
Edited by cooperpwc - 11/2/13 at 10:44am