Thought I'd add a reply here even though it's probably too late!! Might be useful for anyone else considering these?
I have owned the PRE73 and have an Audient Mico. One thing I will say about the PRE73 I owned was it was pretty noisy! This was one of the early original mkI's and according to Bo at Golden Age Projects they did suffer from some noise issues. This has been sorted with the mkII and DLX versions.
The Audient Mico is capable of sounding very clean and uncoloured and can also sound 'warm' with the HMX feature. I was really surprised at how good the HMX sounds and can add a nice subtle thickening to the tone. It is also two channels and has high quality A/D converters and Variphase.
The PRE73 is reasonable at getting you closer to the Neve 1073 sound but lacks the thickness and depth of the original 1073.
The PRE73 wasn't anything special for me. Sounded fine and shouldn't stop anyone from making excellent recordings but wasn't my favourite.
If I wanted a really warm sounding preamp then the WARM WA12 would be a good choice or even their new TB12. Saying that, the HMX feature on the Mico really is very nice indeed and does a similar thing to the sound of the Tone button on the WARM (apart from the 6db boost) but you get 2 channels, high quality A/D converters, Variphase etc!!
When you consider that both the Mico and the WARM preamps are both high quality and the tonal difference we're talking about here are subtle I would go for which offers the features you want and value for money!
The Focusrite ISA One is another excellent option and has a slightly different feature set. From my experience the Mico (UK prices), WARM WA12 and Focusrite ISA One really stand out amongst the competition (and DAV but these are expensive in the US) in terms of both quality and value for money. The are all extremely well made, sound superb and offer different feature sets depending on your requirements. When you consider that the tonal difference's we're talking about here are subtle I would go for which offers the features you want and value for money!
