BAT vk-3ix and Parasound Halo A21 match?

How is the bass

It sounds like you've already read John Atkinson's measurements of the preamp in Stereophile, in which he says that the balanced output impedance "ranged from a very high 14k ohms at 20Hz to 1850 ohms in the midband and above."

It can be calculated that into 66K that will result in a rolloff at 20 Hz in the rough vicinity of 0.2 db, along with some extremely small effects on phase. Both of those effects figure to be imperceptible, and to be swamped by room effects and probably also by the deep bass rolloff of the speaker.

As I have no experience with the preamp, though, I can't comment on its bass performance apart from the impedance matching issue.

Also, given the relatively high output impedance at high frequencies, if the interconnect cable length is particularly long (say 15 feet or more) I would make a point of using low capacitance cables. Otherwise a very slight but possibly audible rolloff of the upper treble could result.

Regards,
-- Al

Yes i did read the stereophile article and did read his concerns.

On the other hand the Thiels only go down to 32 hz so .2'at 20 hz seems ssomewhat irrelevant. I use Purist audio cables which have low capacitance and are only 14' in length anyway.

I went to BAT's website and they say minimum input amp impedance on the amp should be 10k, though I'm sure that is just a guideline.

I guess I'll know for sure once I get it in and hook it up.

I've used my 3ix with a Bryston 3B-SST, which has an input impedance of 10k/leg balanced. It is a few dB down at 20 Hz (measured with a voltmeter at the amp outputs), but nothing disastrous. The Parasound should be fine.

This is the problem you have when you take a chance and just guess on a new component. Preamps are way too important to not get right. Given that, you probably will get lucky. BAT is very well made and should work with a large variety of products. The only advice I can give beyond that, is that if you are not happy, you will not make the situation any better with cables. You may think you will, and when you ask, you will get an endless list of recommendations on what cable you should buy to fix the problem. In the end, though, it just wont work.

Also, it is not clear if you already have the Parasound amp or just plan to buy one. If you don't already have an amp, I would strongly urge you to consider a BAT amp to match the preamp. Doing so can eliminate a lot of problems.