Thanks for your response Pdreher. Now I can forget about the YBA. A few of my friends suggested that the ARC LS-16 might be the culprit due to its clean and soft sounding nature coupled with a low gain. Due to my limited experience with preamps I am not sure if a better preamp may give me the sound that I like. I will keep that in mind. For the record, I have swapped Amperex and Mullard tubes in the ARC and cannot detect any sound difference.
Thanks for the thought.
Thanks for the thought.