Hi Almaatakz
I upgraded from PMC DB1i's to ATC scm19's.
The PMC's are very compact and lightweight, with good bass for their size, but they are a very small speaker, so have their limitations at the end of the day.
The tweeter in the new PMC 'i' range is a lot better than the older models, but it somewhat outshines the bass and mid of the DB1i, therefore drawing attention to itself a little.
Positioning of the DB1i may be a problem depending on your room and distance you have them from the wall/corners. They need some wall reinforcement to help the bass, but their transmission line exits at the rear, so uneaven bass can be a problem near corners etc.
I feel that the PMC DB1i's price on launch of £770 represented good value for money, but not anymore at £1050.
The ATC's impressed me instantly with their tight solid bass, stunning midrange clarity and perfect integration throughout the entire frequency range. No single part of the frequency range stood out above the other.
Bass, midrange and trebble of the ATC's all easily out performed the PMC's.
I realise that there is about £800 in the difference in price between the ATC scm19 and the PMC DB1i, but the ATC scm11 comes in just cheaper than the PMC and gives a very large slice of the scm19's performance in a more compact package.
With your current floor stander/sub combo, i think you will struggle to get the sound you desire from a small speaker. Ive been down that road myself.
Keep the sub and hide it somewhere, and get some decent small speakers. Or sell the sub and buy a smaller one that will fit under the bed or somewhere.
Cheers
Matt