why sound is so different?

Finally looks like was a set up problem,I have done everything from the beguining and now sounds great!, thanks to all for your comments.
As I mention, my cartridge is a Shure V 15 type V-MR. I just found that I can get an interesting price in Ebay so, do you consider would be wise to sell it and buy a new cartridge in the $200-$300 range or is better to keep it? my Shure was made in the 80's and I assume that after 20 years this area must develop a lot or . . . not?

Hdm, looks like the output of this unit is 3.0 mv (the information is in the KABUSA website). I forgot to mention the "MR" in the model so maybe this is why you didnt find it.

Jorsan, I'm using a Dynavector 20XL cartridge.

Again, keep in mind that even with perfect setup, great equipment, some vinyl just sounds like crap. An example:

One of my first LP purchases 4 months ago was Steve Miller Fly Like an Eagle. It was $9.99 and heavy vinyl and I was excited to put it on and hear no surface noise (which was my biggest fear getting back into vinyl). It sounded crappy and when I compared to my CD (which sounded good) I was convinced something was wrong with my setup. Then over time I read more than once that particular LP was a crap resissue. I bought a MFSL reissue on eBay. Got a great copy - no noise or scratches and it sounded better. Today for kicks I pulled out my version from the 70s which earlier I wouldn't even have contemplated playing (I didn't take care of my LPs back then) since it looked in bad shape. Yes, I hear surface noise but otherwise the sound is spot on correct. With the two other versions the bass is raised, vocals recessed and sounds lifeless. This version sounds great.

I made the mistake of thinking that a 'good' pressing was simply a quiet one. I also thought MFSL were the bees knees. I was so wrong. Count me now in the category of preferring a proper/analog sounding mastering with surface noise than a quiet dull or bassy one.

If only I knew this before spending so much money on reissues and expensive MFSL on ebay.

Hope this helps.

Thanks Madfloyd, you're right about the LPs, there are differences between them. Right now Im listening "full sail" from Loggins & Messina and there are songs where the bass is INCREDIBLE. I had a very good luck because from the guy who sold me the turntable I receive an incredible collection of about 160 records of the 70's / 80's : led zep, boston, fleetwood mac, blood, S&T, etc. etc., music that I used to hear in my youth -Im 50 now- and 70% of this records were played just once, recorded in his Nakamichi and thats all, the complete led zep collection is like new, original pressings and sounds perfect, Im very happy with this and think I found a treasure.
Because of this, decided to go shopping in Ebay, but experience there was totally opposite: first record I bought and first discussion with a seller; the way they classify the records is far from what I think is fair or honest, the idea that they have of "Mint", "NM" or "VG+", differs a lot from mine; maybe Im wrong and because all records are old, and I have to accept that -for example- NM means "used with light marks on the record and some ticks and pops", honestly dont know. Maybe some with more experience with Ebay can help here. By the way, are there some hoenst sellers with good reputation there? if yes, who are they?.

By the way, "pops and clicks" in the LPs bothers me lots less than before, dont know why but its true.