Is It Worth Modifying an ARC LS16?

I HAVE AN AUDIO RESEARCH LS16 PREAMP. SOUNDS GOOD BUT DOESN'T HAVE GREAT DYNAMICS OR STRONG BASS.IS SPENDING $1000 TO $1,500 ON THE UPGRADE OR GREAT NORTHERN SOUND MODIFICATION WORTHWHILE OR SHOULD I JUST GO FOR BETTER PREAMP, MAYBE USED $2500 TO $3000? SYSTEM IS McCORMACK DNA1 REV A, VANDERSTEEN 3A SIGS, MICROMEGA DRIVE 1, ARC DAC2, REGA P3, KIMBER 8TC SPEAKER CABLE.