what is serious mass? optimum nutrition?
how much weight are u trying to gain?
u can also just buy any whey isolate plus eat properly.

Serious mass is like the mass more serious lar... it's the opposite of playful mass. But must be careful lar, cause things can get real serious real fast.

Why do you want to change supplement always?
Mass is useless. Just take whey protein if you want. And eat plenty of carbs.

supplement can be considered just food in powder form.

again, count ur calories.
u need something to quantify what ur doing...rather than just say 'im eating alot'...cos u wont be able to track progress properly.
eg. my breakfast sometimes up to 800-900 calories...but i can feel hungry a couple hours after that...cos its not heavy just the food lots of calories.
or i can have a slightly heavy breakfast but only 400-500 calories...so will feel pretty full for next few hours...all depends what u eat.
doesnt mean eat alot means lots of calories.

vege diet plenty of options...u just need to explore more...not just salad.
even mixed rice stalls, lots of tofu cooked diff ways, vegies, baked beans, egg, rice etc etc.
easily can hit 600-700 calories and feel full already.
then if u want add ur supplements to meet more protein...already 900 calories in 1 meal.

then u slowly modify based on ur daily calorie intake...sure can easily take in 2000-2500 calories min every day...