The Fostex FE-103 (which I am guessing is what you have) is rated 89dB sensitivity. Guessing your old room to be around half the dimensions (10x12x8 ft), that would suggest you need approximately 8 times the acoustic power for similar loudness, about 9dB more. To stay with the SEX amp, a speaker with 98dB sensitivity would do the job. Single drivers of that sensitivity are few and far between, and most are compromised in performance to get there. So you would be looking at fairly large, heavy 2- or 3-way speakers; the Klipsch and Pi brands mentioned above have a few suitable models.
In any case, you will need a speaker that can move more air, probably a minimum 8" driver. There are a few 8" fullranges rated around 92dB; that would require an additional 6dB of power, i.e. around 8 watts minimum.
Well, that's a starting point anyhow.
[edited 1PM PDT to clarify]