Wadia 151PowerDAC Mini Integrated Amplifier Review

March 6, 2011
6 mins read


5 Stars

Want to dump those traditional sound sources? Here’s a five star product that makes the future possible.

What’s the best way to describe Wadia’s 151PowerDAC Mini? Some reckon it’s a ‘digital integrated amplifier’, because it only supports digital inputs and because it uses a digital amplifier. The thing is, we don’t call amplifiers with only analogue inputs ‘Analogue Integrated Amplifiers’, do we? Nor do we refer to models with analogue inputs and built-in digital-to-analogue converters ‘Digital and Analogue Integrated Amplifiers’, so I’ll just refer to it as an integrated amplifier and get on with things. [Yes, please – Editor-in-charge-of-getting-on-with-things].

Features and Construction

Wadia makes some of the biggest, boldest and most expensive digital replay components available today. They come in huge, weighty boxes that can provoke a grimace in the beefiest reviewers, so imagine everyone’s surprise when Wadia’s 170iTransport hit the streets. A compact and inexpensive iPod dock from Wadia? It simply didn’t compute, but with its access to the iPod’s digital stream it sure did change the game.

So, what to make of Wadia’s equally small and slim integrated amplifier? The 151PowerDAC (henceforth 151) is built to the same form factor and is meant to be stacked with the 170iTransport or the new 171iTransport. This really is a tiny unit, measuring only 6.86 x 20.32 x 20.32 cm (H x W x D) on its attached rubber cones; it looks completely lost on a conventional audio rack but the size is perfect when matched with an iTransport, and the two units fit nicely on one shelf.

Build quality is first class and the 151 feels solid, and is neatly finished. It also looks good, which is a plus. The metal remote is excellent, certainly way ahead of the plastic fantastic blobs supplied with most amps at the price point, or even those costing much more. Said remote is the best way to drive the 151, avoiding the little amp mounted buttons, and also allows full control of an iPod/iPhone in a connected iTransport.

There’s a small, bright LCD display up front that’s quite legible, even from some distance. You get five small buttons to play with – input, phase, mute, as well as volume up and volume down. On the small and cramped rear panel there’s an IEC power socket and power switch, very nice speaker binding posts and the four digital inputs (2 Coaxial S/PDIF (RCA), 1 TOSLINK optical and a USB). The switching or Class-D amplification is limited to 25 watts into 8 Ohms, but is claimed to double into a 4 Ohm load, which bodes well for the the 151’s ability to drive speakers.

Except for the 24/96 USB input, the Wadia accepts signals at up to 24/192. These are upsampled to 24/384 before being converted from PCM (pulse code modulation) to PWM (pulse width modulation) and passed to the amplification stage. The PWM signal is controlled by a digital volume control, which keeps it in the digital domain until the very last part of the output stage, where it is converted to an analogue signal and sent on to the loudspeakers.

This may sound complicated but the theory is more than sound – handle a digital signal digitally as long as you can and you have more control over that signal. The converse would be “don’t mess with analogue”, which is why we generally don’t convert analogue to digital.

Sound Quality – CD

If Class-D or switching amplifiers can be said to have a signature sound or perhaps a distinctive character, then you’d probably pick something like dry, incisive, clear, maybe even cold. Some might say harsh.

That’s a massive generalisation but the Wadia does embody it to a degree. It’s certainly not what I’d call warm or cosy, but it’s by no means a harsh metallic thing. The overriding impression is one of clarity and insight into the recording, especially at the price, where I believe it has few competitors. In short, the 151 is no high powered arc-welder but it’s not a sonic fleaweight either: it’s got some deep seated ability behind it.

Listening to Steely Dan’s ‘Haitian Divorce’ from Showbiz Kids – The Steely Dan Story 1972-1980 on the 151 from my Marantz SA8260 (via co-ax digital) immediately highlighted the 151’s treble capabilities. There’s a lot of energy up at the top on this track and it’s by no means lost in the mix, but the 151 puts it all on show without making things unbearable. Not even close, at least on these speakers (Theophany M5 Series 2) but I’m not sure I’d be so sanguine with a set of bright metal dome tweeters in the system. Similar thoughts occurred to me with ‘Hey Nineteen’ from the same CD – the treble was beautifully laid out, noticeable but not over the top. Detail on the vocals was superb: you can hear right into the recording here and at the $2K price point, the Wadia is a stellar performer in this regard.

The 151’s limited power output was well suited to the easy-to- drive Theophany floorstanders, but having tried to drive a set of little Spendor S3/5R standmounts with a 25 watt integrated amplifier, I know that it would need to be pushed hard to get any serious volume levels. Stick something reasonably efficient on the end of the Wadia or settle for reasonable volume levels in a smaller room and you’ll be okay; thinking through your component matching before spending any loot is always the way to go.

There’s a sense of speed behind the Wadia’s performance, so transients sounded excitingly vigorous and the music hustled along and never felt less than involving. Bass was prominent, weighty and started off fast, but the ending of the notes wasn’t as as tightly controlled as I’m used to from my existing pre/power amp combination. Not that it was as loose as a boy racer’s boot or even annoying but the last degree of grip seemed to be missing from the equation. However, this wasn’t really the case with the 171iTransport or USB as a source – go figure.

Sound Quality – Paired with the Wadia 171iTransport

I just happened to have a sample of Wadia’s new 171iTransport on hand while reviewing the 151. The $1049 171i has been engineered to support Apple’s iPhone and also has “improved power supply components and step-up audiophile grade connectors”, according to Wadia. It took a few seconds of the first track cued up on my 80Gb iPod Classic for me to register that this was without a shadow of doubt, the best I’d heard an iPod sound. Ever! Then I realized that the Talking Heads track I was hearing was a 320kbps rip, not a lossless or CD quality file. At this point I closed my gaping jaw and started hitting the remote in search of more thrills.

Everything I listened to sounded staggeringly good. So revealing that it felt as if a layer of scunge had been lifted from my eardrums. [Do we really have to imagine your ear scunge? – Editor-of-grime]. Even on the lousy low bitrate files. Clear, open and brilliantly detailed, with a low noise floor, good dynamic range and enough space and air around the recordings to keep anyone happy, even at well above the combined price tag. Strangely, the bass was better controlled and slightly deeper than from the SACD player. The overall sound was marginally warmer as well.

Sonically, you just can’t ask for more than this from a source and amplifier combination at the price, especially one as simple and elegant as this pairing.

Sound Quality via USB

This part of the review is short and sweet. Hooked up to my MacBook Pro, the 151 sounds as good as any DAC I’ve had at home, including models that live in the $3000 price range. In fact, the USB input sounds just plain amazing, with every single one of the attributes I liked about the sound coming from the 171iTransport. I soon gave up worrying which tracks were CD quality and just hit shuffle on my favourite playlist and settled in for the evening.

Gary Pearce and I were talking about this phenomenon recently – many of the DACs we’ve listened to sound brilliant through their USB inputs despite being limited to 16/44. USB actually makes an excellent audio interface. While the Wadia supports 24/96, I settled for enjoying it with 320kbps and CD quality files because I’ve been too busy to get any high res files set up on my system. If it gets better than the CD quality playback, I’m even more sold on this product.


What’s not to like? This is definitely the integrated amp of the future. At times I had to remind myself that I was listening to “only” two thousand smackers of integrated amp. Then I remembered that you’d have to spend between five hundred to a thousand dollars to get a decent DAC, let alone one that supports 24/96. Good luck putting together an amplifier/high-res DAC combination anywhere near this good for two grand.

Sure the Wadia is about as useful as a chocolate oil filter if you’re into vinyl, but if digital is your thing and you’re careful with your speaker matching (from both a sonic and efficiency perspective), then Wadia’s 151PowerDAC Mini is a fabulous buy.

Plug in your computer and you’ll be stoked, or pair it with the 171iTransport (which provided the best overall sound of the three sources) and you’ve got the makings of a superlative compact audio system with nary a CD player, computer or turntable in sight (and yes, it does pain me to write that last bit). Still, the same outlay gets you into something like Perreaux’s more versatile Audiant 80i integrated, which has more power, a few analogue inputs, a MM phono stage as well as a built-in DAC (only 16/44 USB though).

What I’d really like to see is the 151’s DAC internals in the same chassis sans the amplifier section. Fortunately Wadia is way ahead of me, and will hopefully be releasing the much delayed 121DAC at some point in the near future. This apparently has all the digital inputs of the 151PowerDAC along with the upsampling and the digital volume control. Bring it on and keep the price down please, because it could well be the preeminent reasonably priced DAC choice. It’s definitely a good time to be a music lover. ASHLEY KRAMER


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