It might be difficult for anyone in the USA to help much, mostly because we're not sure what is available in the Ukraine (at least I'm not sure, anyway). SVS is definitely good, so that is an option. Can you get Rythmik, Hsu, XTZ, Martin Logan, Epik, Mordaunt-Short, Focal, Tannoy or Rel? All of those companies make good quality subwoofers.