Frankpiet--not at all. The 31SE is a great preamp at prices on this website. It just isn't a 51SE---just looking at the build quality alone, its quite obvious. I spoke to BAT on this, and they think the 31SE perhaps is the great bargain---though it definitely isn't the 51SE. The 51SE is even more transparent, liquid, and forceful in the bass. It exudes a "blackness" to the background that needs to be heard to be believed. Good luck!
