Your machine is very good, i have the 680 model, one of the best home espresso machines in the market.
Some thing seems weird, you are using the pressurized basket that came with the machine, that mean you dont have any control over your shot time, the basket is calibrated to give you 15 sec pull time in single shot basket, anf 28 sec in the double shot basket, no matter what you did the machine will give you these times assuming you use the ground coffee you buy from the market which is what it is desingned for, to work with pre ground coffee, if you have a grinder you should set the grind size as close as possible to the pre ground coffee size of you want to use the pressurized baskets, which i recommend you to do, that way you enjoy the freshness of coffee with pressurized basket, that will give you a good shots.
Non pressurized baskets will give you better shots but needs experience and a good grinder, if you are just starting with espresso keep it that way for now, and learn how to pull good shots with pressurized baskets first.

I do have the same problem. HOWEVER.

I have freshly roasted /approx. one week and a half/ beans.
I've got Mahlkonig (Baratza) Vario, VST 17g baskets, good fitting tamper and I'm using a NS Oscar 2 with OPV.

Funny thing is, that even when I adjust the grind settings to a finer setting - I will only hit 12 seconds (From the point of first drops into the cup) - 17g in, 35g out.

The espresso does look and flows better with finer settings but the time absolutely does NOT change.

Any tips? I'm kinda lost. The espresso is bitter and sour at the same time. Not really watery, but lacks the complexity. Its like sound with full bass, full treble without any mids. I enjoy this brand long enough and this is not what I should get.

I had the 685 before I got my current machine. It only comes with pressurized baskets and it should be dead simple to choke the machine with any brand of coffee, I think. I never found one that didn't choke it at some setting. I had a Hario Skerton hand grinder but it didn't have enough settings to really work well with this machine. I seemed to either choke the machine (and then had to clean the group by unscrewing the bolt for the shower screen, or got shots that were too quick.. about 15-20 seconds.

I never easily got 30 second pulls..

the other problem I found is that I could only get about 12g of coffee in the double basket, which was not enough if I was making an 8 oz latte.

I never got the rich espresso taste that I can now get in my HX.. I see on YouTube some people trying $300 and $3k machine and not being able to tell the difference in espresso.. I think they have very bad palates..

But if you can't choke your machine, your grinder is not grinding fine enough. Maybe take apart and really clean well.. try again.

SmartFish wrote:I do have the same problem. HOWEVER.

I have freshly roasted /approx. one week and a half/ beans.
I've got Mahlkonig (Baratza) Vario, VST 17g baskets, good fitting tamper and I'm using a NS Oscar 2 with OPV.

Funny thing is, that even when I adjust the grind settings to a finer setting - I will only hit 12 seconds (From the point of first drops into the cup) - 17g in, 35g out.

The espresso does look and flows better with finer settings but the time absolutely does NOT change.

Any tips? I'm kinda lost. The espresso is bitter and sour at the same time. Not really watery, but lacks the complexity. Its like sound with full bass, full treble without any mids. I enjoy this brand long enough and this is not what I should get.

Likely sour, not bitter.. sounds like one problem could be channeling.. How are you distributing your grounds before you tamp.. I generally fill the basket 1/2 full then rap to get the grounds even then tap the bottom of the filter basket on the table to get the bottom settled, then fill rest of grounds and repeat. Then tamp. The best way to fix problems here is to use a bottomless portafilter and look at how the flow comes out into the cup. Lots of info on it on these forums.

If you can only hit 12 seconds your grinder is not grinding fine enough.

The espresso is bitter and sour at the same time.

Usually, this is the sign of a grinder with bad particle distribution. But, I see you're using a VArio, which isn't known to have such problems. So, Dave is probably right about the channeling. Still, you might try that app that analyzes your grind, or at least spread some out thinly on a paper and look with a magnifying glass for a bad mixture of excessive fines and coarse bits.

Hmm, never really checked the grind like that. I might give this a try.

The channeling could be a problem of course. I dont have the naked portafilter to confirm yet. I will check the grinder too. Im sure Vario should give good results.

Regarding distribution, I use two methods. Either I cover the portafilter with my blind basket and I make this light spinning movement. I'm sure you know what I mean

The second method is light finger tapping around the portafilter, followed by a tap from below to collapse the pack. Then tamp.

When I tamp, I never spin or anything. Just simply put in the tamper, feel a bit around with fingers and when even, press once, max twice on the handle.

Bluenoser wrote: I never easily got 30 second pulls..

The machines with pressurized baskets are engineered to have that regulating the flow, they basically place a flow regulator (in the form of the small hole) after the coffee grind, thus taking away the grind as variable. The point of doing so is that a big range of grinds can be used in the machine without changing the flow, you really need to go to extremes to start seeing a difference.

Bluenoser wrote: the other problem I found is that I could only get about 12g of coffee in the double basket, which was not enough if I was making an 8 oz latte.

Thats what they are meant to hold, born to work with that, they give you a measuring spoon too, and it wont go beyond that amount. You are supposed to adapt your milk to the coffee not the other way around. If you depressurize or adapt a bigger depressurized basket making a decent shot its a matter of having the right beans, the right grinds, the right ambient temperature, the right mood, the right planet alignment, the right blessing from the right god and all the saints of the calendar lending an hand...

Bluenoser wrote: I never got the rich espresso taste that I can now get in my HX.. I see on YouTube some people trying $300 and $3k machine and not being able to tell the difference in espresso.. I think they have very bad palates..

To a point you get what you pay for, and if one tries to use a tool beyond the limits it was designed for...
People have different palates thats all, and an experienced user can make so that even the 300$ machine gets a fighting chance.