Xindak XA8250/XA8800MNu Review

Xindak XA8250/XA8800MNu
Pre/Monoblock Amplifiers

This issue, I was scheduled just to review the recently introduced 130 watt Class A monoblock power amplifiers from Xindak. When they arrived, I noted from the literature that accompanied them, that the company also made a matching preamplifier with balanced inputs and outputs. Well, you try and find a balanced preamplifier available on the market at any less than silly money; there aren’t any. So I rang editor Nic Tatham to see if we could include the preamp in the review and he agreed. A quick email to Melbournebased Final Link Audio Pty Ltd, the distributors of Xindak, and we had one on the doorstep within a couple of days. Final Link Audio’s managing director, Shane Lewis, was also very enthusiastic to inform us that this review would be a ‘world first’ for this Xindak combination.

Before the preamp arrived, I had a chance to run in the Xindak monoblocks on my reference set-up, consisting a Cayin CDT-17A valve CD player at the time feeding an Audible Illusions Modulus3 valve preamp with the monoblock power amps driving my resident Magneplanar MG-1 loudspeakers. What was immediately noticeable was that the Xindaks were warm and smooth, almost valve like, which is exactly how the accompanying product information described them and I quote, ‘select materials endow this unit with mellow sound.’ Well, it certainly got that right. Additionally the literature also describes them as having ‘excellent low frequency control, powerful drive, dynamic with extended soundstage, transparent, elegant and vivid with high current driving ability.’ Sounds like everyaudiophiles dream, so we will just have to see.

The Xindak XA8800MNu monoblocks are made in China, (but you probably already guessed that). They are a very neat and tidy, compact design. The casework features a chunky shotblasted, silver anodised aluminium front fascia with a large illuminated push button power switch. An exposed, black heatsink runs down the right hand side of the enclosure and a rear panel is well fitted out with a gold plated machined RCA unbalanced input, a XLR balanced input, input changeover switch and two sets of shielded gold plated WBT type speaker sockets for biwiring.

Internally, it is equally impressively engineered with fine layout of the internal hardware and good constructional standards. Excellent quality components mounted on fiberglass PCBs, some 60,000 microfarads of Rubycon reservoir capacitance, Motorola, Toshiba and Sanken audio grade output transistors feature in the design, with a few exotic Black Gate, Xindak and Rubycon capacitors sprinkled about in critical areas of the circuit. The circuit topology is a bit unique, it features a Burr-Brown OPA604 balanced to unbalanced buffer IC with input relay muting, feeding a low distortion, discrete transistor symmetrical differential voltage amplifier which in turn drives a threestage fully symmetrical current amplifier output stage. There are separate windings on the high current toriodal transformer supplying power to the various stages within the amplifier, together with separate filtering and voltage regulation, keeping interaction between stages and intermodulation products to an absolute minimum. Xindak’s designers have certainly done their homework with these amplifiers.

Being a Class A design, means they get hot. I did some measurements and a quick calculation showed that the output stage is dissipating 163 watts at idle with no signal. With the nature of Class A this will remain fairly constant and may even reduce under normal listening conditions, but it showed that the design is not fully Class A for it’s total power output, only the power considered necessary to accommodate, say 100 per cent of what you would be listening to, 95 per cent of the time. This is sensible engineering. The design engineers at Xindak have also incorporated comprehensive protection circuitry covering thermal, over current and DC offset protection to cover the amplifier and your speakers. With the Xindak preamp now insitu, let’s hear what it has to offer. Again, stylishly simple as with the power amps, three position input selector, illuminated power switch and a volume control supported this time on a thicker 20mm alloy fascia with the width slightly larger at 305mm than on the monos. The rear panel again supports machined gold plated RCA sockets for the two unbalanced line inputs and line outputs as well as two sets of XLR sockets for the balanced connections.

Internally, again there has been careful engineering input to achieve the sound that Xindak wish to accommodate. Separate power transformers with loads of independent filtering and voltage regulation feed the dual mono design, with all the input switching handled by relays located close to the input sockets. Burr-Brown OPA134 buffer ICs are used on the balanced inputs, a discrete transistor gain stage with fet output follows together with a interesting output Audio & Video Lifestyle Magazine 68 coupling capacitor configuration that I have not seen for a while involving biasing the array to mitigate the effects of having a capacitor in the signal path - nice touch.

So with all of that technicality out of the way, we had better hear what all of this actually sounds like. The Cayin and the monoblocks were connected up with the balanced leads to the preamp and the first few discs into the tray left me a bit amazed to be quite honest. The sound was quite warm and very smooth, which did not surprise me at all because that was a obvious characteristic that I heard the first time I listened to the monoblocs, but what did surprise me was after connecting up the Xindak preamp into my system was the level of detail I was hearing from the Cayin. Familiar recordings sounded different, there was a greater level of transparency, and a lot more low-level detail extracted from the recordings, a lot more space between the players and the soundstage was much deeper. Thinking back, the diminutive 12 watt Leben CS-300 valve integrated amplifier which I reviewed last year in Audio & Video Lifestyle (issue AVL-174) had a very similar characteristic. You were listening to more music and less electronics; veils were lifted, giving you greater insight into the recording, difficult program material was unraveled with less confusion. So I thought I’d better start getting down to the bottom of this and analyse what’s doing what.

To start with, I reconnected my familiar ME 1400 power amp back up. The ME has balanced inputs so we are just taking the monoblocs out of the equation. Then I had a good listen. Gone was the warmth of the monos, but also gone was some of the smoothness that I noted that Xindak possessed, I put the monos back in circuit and sure enough the warmth returned, but so did a degree of clarity to the midrange and treble over the ME. I would say that from 150Hz upwards, the Xindak had it over the ME in sound quality, which was surprising! The vocal quality was much better; a more natural timbre as was the clearer, cleaner, delicate treble. The amplifiers seem to be free from any harshness or grain and I found that I could be unconsciously be listening to music at a higher level than I would normally would be with the more powerful ME and it was hard to make them step out line; they did not harden at high volume but started to compress instead, very much a Class A and valve characteristic. But that’s only part of the story and there are other issues at stake.

The next step was to substitute the balanced connections back to unbalanced RCA lead operation and this was done in two stages. Firstly, the CD player to the preamplifier as this was easily achieved by just connecting a RCA lead to a unused input of the preamp and switching from one to the other altering the volume to suit as the balanced connections give you a 6dB lift in level. Instantly the soundstage shrunk more to the centre using the unbalanced connection, switch back to balanced operation and every thing opens up, more space around the performers, greater width, more depth to the soundstage, greater transparency and better dynamics - quite remarkable. The lead swap at the preamplifier output to the amplifiers had a lesser, but similar result, so there was no question about the benefits of going fully balanced; it’s the only way to go.

So impressive was the sound that was achieved with these Xindak products I am having a serious rethink about my reference system, some aspects of it have never sounded better and I was diving deep into my CD library finding new details in the music that has been so familiar. The sound was very intimate and so involving that I just could not stop listening. Club jazz, classical and vocal material were sure winners with maybe hardcore material demanding a bit more authority that the ME possesses. In conclusion, if you have a CD player with balanced outputs, I would definitely recommend that you utilise that facility and the Xindak XA8250 preamp will certainly do the trick of integrating XLRs into your system. It’s transparent, detailed and open, it comes with a remote and is extremely good value for money at $1,899. The Xindak monoblocks are another gem; they are so detailed and smooth that they put expensive high-end amplifiers to shame, but they are on the warm side. The overall sound was reminiscent of some the highly regarded Pass Labs designs. I could see them working well with a lot of loudspeakers on the market, but if the speaker is already bass heavy, this characteristic might be too overpowering.

As always, the only way is to audition and hear for yourself; a dry, detailed loudspeaker would be an ideal match. These amplifiers would be perfect for those jazz afficiados, Class A freaks and people who love valve sound, but don’t want to muck about with valves; they have all the attributes, without the fragility. At $2,499 a pair they are a steal, representing great sound for high-end 2-channel or above average high-end home theatre situations. There is also a bigger brother, the XA-8800MNu 200 watt Class A monoblocks available at $4,499 a pair in the US - I’m drooling at the thought of a listen.

Both of these products offer fantastic value for money and provide unparalleled performance at this price-point. Want a taste of true highend amplification a beer budget? Definitely check out these babies. AVL Ancillary Equipment: Cayin CD-T17A CD player, ME 1400 power amplifier, Audible Illusions Modulus3 preamp, Roberts Audio passive preamp, Magneplanar MG-1 Improved panel loudspeakers.

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