Just remember that NO protien shake will replace whole food. I am on the constant search for mass and have been very successful without the use of protien shakes. Currently I'm 6'2" and 230 pounds. What do youy think bodybuilders were drinking 30 years ago? Designer Whey?! Hardly. The amount of 1.5 grams-2.0 grams of protien is a little exaggerated because protien manufacturers want you to guzzle down enormous amounts of protien! They make a TON of money off your notion that shakes will make you huge.
The amount of protien you need is all relative to how much intensity you are using in your training. I know of guys that go to the gym, lift 20 pound dumbbells 6 times than go and do 4 reps of squats ( and dont even go all the way down) and than expect that a protien shake will make them huge! haha
If you want to gain wieght my friend, focus on eating a more reasonable amount of protien such as 2 garms per KILOGRAM of LEAN body weight. Remember we are not feeding FAT, we want to feed MUSCLE. EAt 15-20 times your weight in CALORIES and eat often! I eat every 2 hours on the dot and this keeps my body constantly in a high state of metabolism, which helps keep me lean. It's kinda simple, to gain weight one must eat LOTS and eat OFTEN! If you had any idea as to how much serious weightlifters eat, it would make you sick to your stomach! Of coarser these are guys that are on another level but the rule generally stays the same.
Remember you have to eat,eat,eat,eat and eat again if mass is your goal!
Your only as strong as your weakest link!
I realize this is a very short answer to a question that can be a little more complicated than what is explained. If you have any more questions about training or protien, etc, there are a few of us here that I am sure can help. Later.