I finally have it :) Ruby is the solution I was looking for and it would be perfect for traveling. On hot days, you need to take a break a bit more often for a sip of water, because sometimes there is not enough air inside. It is necessary to work out the equalizer settings, but results are outstanding! This is feedback from sound engineers I cooperate with: "I don't hear any difference. You're really on the road or just teasing with me?", "It sounds very good. Equalizer is needed but the final effect is awesome", "For me is totally fine. You can send such recordings with no problem", "I have no objections to Ruby, I do not hear the room reverb, there is practically no difference in relation to a stationary studio."