Hardware Reviews

BorderPatrol DAC SE to tube or not to tube


BorderPatrol DAC SE digital to analogue converter

BorderPatrol is a small company whose proprietor Gary Dews started out working with Audio Innovations (which became Audio Note UK), so you won’t be surprised to learn that its speciality is tube electronics. Gary was originally based near Brighton in the UK but moved to Maryland in the US some time ago and has been quietly making his mark, he’s not one to make a song and dance and takes an unusually stealthy approach to marketing. BorderPatrol’s trademark would appear to be choke input filtered power supplies, as a result Gary’s power amplifiers have more grip than most of their ilk. The subject of this review is not an amplifier however, it’s a fairly modest even minimalist digital to analogue converter.

The BP DAC SE is available as a coax or USB input converter (or both for a bit extra) that’s fairly compact (9 inches/226mm wide) and unusually engineered. That button on the front is not an on/off switch, which is on the back, it’s to turn the tube in the power supply on and off. This vacuum tube doesn’t sit in the signal path at all but works in parallel with the solid state diode rectification when engaged. Gary recommends turning off the tube when not listening critically to lengthen its life. The solid state section of the power supply is also ‘snubbed’ in such a way as to slow down the high speed switching of the diodes which causes pulsing in the power supply and creates bursts of high frequency EMI (electro magnetic interference) that ultimately has an effect on the signal. It’s well known that power supply quality affects sound quality but rare to hear this particular argument. But then again tube rectification is pretty uncommon in DAC power supplies as well


It’s not the only unusual aspect of this DAC, in true BP style it has a choke input filter on the power supply featuring an “over size power transformer”. This model also features an ELNA Cerafine power supply capacitor and film and foil signal coupling caps, an old favourite with the SET brigade.

The actual converter in this DAC is described as a non-oversampling R2R chip, which roughly translates to one of the Philips multi-bit chips produced in the nineties that are usually described as NOS (new old stock) and used by a few brands including CAD. Modern DAC chips are delta/sigma types that can handle high sample rates including DSD and are essentially 1 bit devices, the one in the BP is a 16-bit type that Gary specifies as being good up to 96kHz, however they generally work at up to 176.4kHz, which extends the range of high res recordings you can play but not significantly.

Build quality is utilitarian but high; this is a well put together box and I like the way that the EZ80 rectification tube is exposed in a little bay. The front panel switch is a little recessed and even more so when it’s depressed but a blue LED brightens it up. The single ended socketry for output of both analogue and coaxial digital signal (in the USB only version) is of a high quality and build inspires confidence in this DAC’s longevity, as does its maker’s 30 year tenure in the market.


The BP DAC caused quite a kerfuffle when it was reviewed several times over by Stereophile, the first piece praised its musicality and realism but when the editor measured it his pronouncement was rather more critical; tubes and NOS chips have never measured well after all. It was subsequently sent to another reviewer on the same title who said it was not as good as his Benchmark reference but was so musical and easy on the ear that his wife wanted to buy it. His friends from the local music society all expressed a preference for the BP over the Benchmark saying it was more natural, made instruments sound more like real instruments and that it would be much easier to live with and enjoy day to day. Altogether, quite a helpful controversy that must have done wonders for BP’s profile in the US and beyond.

BorderPatrol sound quality

When I first fired it up this DAC had less depth of image, a more forward balance and a relaxed sense of timing compared to my reference, but it wasn’t long before its charms became apparent. I had the BP connected directly to the USB output of the Innuos Zenith SE with a CAD cable which seemed to be a good partnership, so much so that the music became unusually compelling. I put on Beethoven’s 5th(corny I know but the Barenboim version is pretty good) and found it to be rather more difficult to press stop than usual. The dynamics had impact without needing to raise level and were in perfect proportion to the music, the effect was so engaging that I found myself listening to the whole movement and continuing with the one that followed. This does not usually happen, it’s a great piece that’s well played but I’m only a part time classical listener. This was with the DAC in its tube rectified state, I found with extended listening that acoustic material always sounded more enjoyable in this configuration, this despite the presence of very little obvious tube character in the sound. The DAC SE after has no glass in the output stage whatsoever. But the rectifier makes its presence felt quite quickly and helps to create musical entertainment that’s very difficult to put down.



Non acoustic material lacks a little bit of its power with the rectifier but switching it out turns the BP into a distinctly better than average converter, and you can make the change whilst its playing with no nasty noises. The way to get a nasty noise is to play a 192kHz file, it’s not horrendous but neither is it encouraging. Higher sample rates elicit no sound at all as I discovered when trying to use an Auralic Aries G1 streamer that was set to upsample to 384kHz. Once sorted this addition to the circuit did prove beneficial, adding to the DAC’s uncanny knack of unearthing the music from the sound. It’s no use putting on the audiophile favourites in the hope of hearing more glorious tone or more spectacular imaging, it does both adequately well but the focus is always on the composition and its performance. Something that few audio products really master and even fewer digital components. This was made clear when playing Alva Noto and Ryuichi Sakamoto’s ambient beauty Summvs which has some fabulous bass notes. This had excellent scale in the BP’s hands but the bass was more gentle than usual albeit plentifully deep. What it gained was musical structure, I don’t play this all the time but can honestly say it has never sounded more musically coherent and engaging. Usually it does what ambient music does, makes for a great backdrop, now it was pulling me in. This is a quality you get with record players but one that digital rarely achieves, so it’s quite an achievement by any standards let alone in a relatively affordable product.

Timing is not eager but seems very natural, there is something intrinsically right about the way the BP presents music, acoustic music in particular. But I also played a lot of non acoustic tracks through it with the tube switched out and enjoyed every moment. It’s not as tight and solid in the bass as the solid state alternatives but it is a lot more coherent and engaging which suggests that it’s doing most things better than much of the competition. The fact that it measures so badly but communicates so well suggests that the wrong parameters are being measured. You can tell a lot from careful measurements but ultimately they don’t tell you whether a product is truly rewarding when it comes to emotional engagement, and that for me at least is the point of the hi-fi exercise.



BorderPatrol verdict

The inability to cope with higher res signals and DSD limit its appeal to the hard core audiophile perhaps but anyone interested in getting maximum enjoyment from their digital music collection should seriously consider this DAC. It’s sold direct by BP which means that the price is impacted by VAT and import duty, which is not the case if you are in mainland US where shipping is free too. There is no option to try before you buy but  BP does offer a 14 day return option if you pay for shipping. However, there is a danger that you will fall for this DAC big time and if you want a converter that puts back what the digital recording process loses I can think of few better boxes for the job.


Type: Multibit digital to analogue converter with valve rectification
Digital inputs : RCA coax and/or USB
Digital output: RCA coax (single input model)
Analogue outputs: single ended RCA
Headphone outputs: none
Formats supported: PCM
Sample frequencies : PCM up to 176.4 kHz
Weight: 3kg
Dimensions HxWxD: 78 x 226 x 173mm
Colour: silver and black

Price when tested:
USB or SPDIF $1350 (approx. £1,200 inc shipping, duty and tax)
USB + SPDIF $1850 (approx. £1,500 inc shipping, duty and tax)
Manufacturer Details:

T +1 301 705 7460



digital to analogue converter


Jason Kennedy

Distributor Details:

Kaja Music Systems
T +1 301 705 7460

Notify of
Inline Feedbacks
View all comments