Abbas Audio tube line stage

I am looking for a tube line-stage to do both impedance matching and volume adjustment.

I've read very good comments about Abbas Audio products. The problem is that their website is in Russian:

Добро пожаловать на сайт хорошей музыки abbasaudio.com

I translated using google but I didn't understand that much. I tried to contact the company both from website and their ebay writing simple phrases translated using google... but no answer!

Does somebody know their line stages products? I understood they do two lines stages

Abbasaudio, tubo preamplificatore, 6N6P + 6C4P (vicino a 6X5), guadagno 20db | eBay

Предварительный усилитель(Буфер) на 6Н23П(ЕСС88) - Предусилители и буферные каскады - Abbas audio

Although one is only available only on ebay, the other only on their website. Translating those pages from Russian I understood that these circuits are done as buffers/or output stages for DACs

I wanted to ask some questions that I report here just in case somebody has dealt with this:

1. can these circuits work as a usual line stage with a volume pot attached after for doing volume control?

2. I wonder what are the real sonic differences between the two.

I hope somebody has some piece of info on this interesting company.