I'm having trouble perfecting my espresso with my stainless steel stovetop espresso machine. As a preliminary matter, would you please confirm whether these contraptions are capable of making excellent espresso? I was under the impression that stovetop machines were among the best for an authentic espresso, the only drawback being ease of use/cleaning. However, I've been research this a little, and have read that real espresso cannot be made on the stovetop because it cannot create enough pressure. Which is it? One problem is that I get a lot of grounds in the cup. My beans are ground at the grocery store on the 'espresso' setting. It's pretty fine. In the cup, it collects at the bottom looking like sludge. If I get it ground any coarser, it won't be 'espresso'. Should I opt for a slightly coarser ground? Drawbacks? The biggest problem is that I get no crema. Overall, I think the espresso tastes pretty good. How important is crema, if at all. Is it just hype, or a necessary component of a proper espresso?