I use a Bose Soundlink Mini (currently £150 on Amazon) for this exact task; streaming Spotify and YouTube. Used it every day for four years and still going strong. Fantastic sound quality for the price, portable, looks good and I get at least six hours from the battery when I take it into the garden.
Can connect to your phone(s), tablets and computer which you can then alternate between. The Mini version works well as I like the portability though the have other larger versions.