The Ortofon cartridge has an output of 4mV..
And when played through the 3490's phono preamp, or the external one U posted both of the phono preamps
do not have enough gain to match the output level of a high level source such as a CD. They will work fine for general playback levels but when pushing for high volume levels U run out of gain. Also note that the level recorded on each vinyl disk can vary significantly as well. Other factors come into play for the entire system including amplifier power output and loudspeaker sensitivity.
Note that I am very aware of the 3490 electrical performance specifications as I was the original product engineer that sourced/developed that product..
I have alot of experience for phono preamps, cartridges, different vinyl disks. I actually have 10 different phono cartridges that I have accumulated over the last 20 years, plus a very large vinyl collection of direct-disk, audiophile pressings. For my system, my primary choice is to use a Yamaha pre-amp, Denon moving coil cartridge & stepup transformer, high-end Marantz turntable all run through a very powerful pro power amplifier coupled to some floor standing JBL tower loudspeakers. So I can crank the levels way up there but note the $ investment is 10X the cost of the 3490 and Rega TT.
If U are serious about vinyl, I would suggest U send back the other phono pre-amp, and purchase a Parasoun Z-phono preamp. The ParaSound has 46dB of gain compared to the 36 dB of gain of ur external phono pre-amp.
Here is a link to the Parasound unit...
http://www.parasound.com/zphono.php
The additional gain of 10dB should be enough to bring up ur expected volume level.
Post back if more questions..
Just my $0.02...