I've had a LSA VT-70 for about 6 months now and really enjoy it. It has performed flawlessly with a pair of Spendor 4/5 bookshelf speakers which are only 84 dB sensitive. It has no problem playing them well past my desired average listening level of around 85 dB.
I guess my question is, with your Forte's, which are 98 dB efficient, why are you going for the extra power of the VT-150?