McIntosh MC240 Amplifier sound?

I recently took delivery of a restored MC240 amplifier. It came with non-descript Chinese tubes. I replaced the 6L6 with vintage RCAs and am awaiting a compliment of Mullard Telefunken mix of input tubes. At this point I find the sound to be very soft and lacking any definition. Is this typical of what I can expect with this amp or will better tubes transform the sound significantly? I'm rather surprised since from what I've read, this amp is considered to be 1 of the better amplifiers McIntosh produced all those years ago. Frankly its the softest sounding amp I've ever owned and there have been several over the years. Any observations are welcome especially those who have owned or own an MC240.
I'm using a pair of Tannoy Canterberry speakers which are 96DB efficient. I've used a few other amps and they've all been very compatible including some 8 to 10 wat amps. I'm wondering if using other than 8 ohm tap might prove better. Frankly and so far, this is the softest sounding amp I've ever encountered. I'm expecting more from it! I'm going to try a different set of speaker cables to see if more definition is wrung out. I'll try a set of Morrow speaker cables.
Have you checked to make sure all the input tubes are the correct ones? Also, during the restoration, were the replaced parts done with correct values?