The MHDT Stockholm V2 is the second revision of Stockholm DAC, which was conceived as a successor to the Havana non-oversampling DAC, with the additional capabilities of playing high resolution audio.
The Stockholm uses the same DAC chip of the Havana, the PCM56P-J, with a different USB receiver chip digital filter (CS8416) which takes in up to 24/192 material.
Albeit being capable of playing hi-rez material, the digital to analog conversion is performed by a 16 bit chipset, and is going to perform at its best with 16/44.1 music. High resolution music will still sound good but some of the available resolution will be truncated, hence, high-rez audio compatibility should be taken as an addition, but not as the core feature, the DAC being optimized for redbook audio.
The MHDT website doesn’t show much information regarding difference between Stockholm V1 and V2. Apparently, the primary difference is in output voltage. The original v1 Stockholm had output voltage of 1.1v, while the V2 is 3v, making it more adapt even with less powerful systems, which could have sounded anemic with the first revision of the DAC.
The Stockholm is a beautiful looking piece of hardware; its vintage feeling is emphasized by the glass front panel and its tube output.
Especially in black I think it’s very elegant.
Connectivity and test system
The Stockholm can take coax (RCA), BNC, Toslink and USB digital inputs, up to 24/192. For the purpose of this review I have used Audiophilleo 2 connected to the RCA and BNC inputs, and I have compared it to the native USB input.
I have used Headamp AE-2 with Etymotic ER4P and AD2000; I have also played with Babystax (custom upgraded Stax SRS-001 Mk2 portable amplifier and earspeakers).
The Stockholm approaches the music with a combination of relaxed midrange, powerful bass (albeit lacking ultimate depth), shiney, but not piercing treble, wide soundstage.
The resulting sound is full bodied, a bit charged, dynamic, very detailed. It is helpful especially with older type of recordings, which tend to sound softer, slightly glossy and more pleasing, very detailed without any harshness.
The Stockholm is a very good pairing with Audio Technica AD2000 out the AE2 amplifier: the gentle midrange and slightly U-shaped signature make for an easy listening, with wide and deep soundstage, and focus on microdetails without any sibilance.
The constant feeling, when wanting to listen to music, is to choose the Stockholm in order to have and easy, immersive and pleasant listen.
The Stockholm V2 scales well with Audiophilleo 2, compared to the integrated USB input. The Audiophilleo makes spatial positioning and the soundstage much clearer: spatial details (the “sparks”), with their own path of drifting, are more easily spotted instead of just disappearing. This clarity of perception adds up to the sensation of delicacy and sense of ‘control’ over the music.
There are several sources on internet as to how to improve the Stockholm using different parts.
Among tubes, the most loved choices seem to be Bendix / Tung-Sol 2c51 and Bendix 6385. The former is considered better for tonal richness, while the latter has a little better definition.
The PCM56 chip can also be upgraded with a PCM56-K (K-grade), or with an AD1865. The latter chip is a bit more detailed and less rounded than the PCM56 family, and might be better matched with the 2c51 tube.
Signal capacitors can also be upgraded to Blackgates, Vcap or other high end ones.
On Head-Fi there is a big thread where to find lots of suggestions.
Conclusion and pairings
The Stockholm 2 offers a sweet, effortless and energic presentation, which makes for an unfatiguing listening flow. The DAC tonality is in the middle between neutral sounding gear (like the Audio-gd NFB9.2 or the Antelope), and the more analogue sounding gear (such as Idat-44m or Audio Note).
I see it as an especially good match for Audio Technica headphones (like the AD2000), Grado’s, several orthodynamics and fast sounding headphones in general.
The thickest headphones, like Sennheiser HD650, might not enjoy the most out of the Stockholm signature.
Given its particular signature, it can pair equally well with tube and solid state amplifiers if carefully matched.