Your turntable is not very high quality, so the built in phono-preamp (feeding the line out) is not very good. Trouble is that an outboard phono-preamp of better quality would probably not help greatly given the quality of the turntable/cartridge combination. Whether to use the line out, or feed directly to a phono preamp, or to phono section of an amplifier, is a question I could only answer by listening to it both ways.

If I were in your shoes, I would start saving for a better turntable/cartridge right away. I know you probably didn't want to hear that, haha

As for your first question, I'm not really a tube guy, though my phono preamp has tubes!

BTW- Except for the nice airy softness of tube amps, we have the same sound preference :)

I assume that you understand that you cannot just switch to the other switch position unless you either have a separate phono preamp or your amplifier has one.

By putting the switch in the "LINE" position you are routing the signal through the phono preamp built into the turntable, which performs RIAA equalization and brings the signal up to 'LINE" voltage level.

In addition to providing a LOT of amplification, the phono preamp also puts the signal through an RIAA equalization filter, which is absolutely mandatory.

When music is recorded on a record, the bass is reduced A LOT and the treble is boosted a lot also, becuse of phyical limitations of the record-cutting lathe, among other things. The RIAA equaization must restore the correct frequency balance or the music is virtually unlistenable. 

If you are not familiar with this, I suggest that you read the Wikipedia entry "RIAA Equalization".

You can probably make a major improvemant by getting a better phono preamp and switching the turntables phono preamp out of the path.

The one I would recommend is the Musical Fidelity V-LPS; it is really excellent.

I wonder what you mean by bass, because the S30 speakers are too small to produce any real bass. They are only rated to go down to 55 Hz, and they are already down in their response at that frequency.

You might want to consider looking at a pair of Wharfedal Diamond 10.2 speakers, which are better  speakers and have quite a bit of bass capability.

If I may butt in here as I have a similar dilemna. My turntable, a Stanton T.90- as I have been told- is also low quality. I have probably about 300 LP's and just as many 45's. To upgrade, I would have to spend some $300 or more dollars, as I have come to realize.

The problem is that I have somewhere around 3,000 songs on a couple of USB sticks that I plug into a Yamaha CD-S300 that has a Burr/Brown DAC that, admittedly, now makes my turntable sound muted and lifeless. And that, as I know, is the tip of the iceberg when it comes to what kind of quality is out there with DAC's. Before I purchased the CD player, the record player was top of the pops. Now I have a remote control and move from folder to folder rather than putting the needle on the record. It feels like 1985 all over again.

I like spinning records, but I have come too realize that spending money on a new turntable, phone preamp, cartridge...I just feel a better "investment" can be made elsewhere for you Kilgore.