Replacement for Nested SELECT statements for every row in SELECT clause
It's the classic EAV pattern, which is a strong indicator of a design issue. I hope you understand that this design is against the core rules of relational databases. I have a blog post on this subject if you want to dig deeper.

However, if the design can't be changed, you can use a PIVOT query to extract your data:

DECLARE @BaseTable TABLE (
    IDKey int PRIMARY KEY,
    Name varchar(50)
)

INSERT INTO @BaseTable
VALUES
(1, 'Ian'),
(2, 'John'),
(3, 'Ann');


DECLARE @Table1 TABLE (
    ID int,
    Amount int,
    Type char(1),
    PRIMARY KEY (ID, Type)
)

INSERT INTO @Table1
VALUES 
(1, 100, 'X'),
(1, 200, 'Y'),
(2, 300, 'X'),
(2, 400, 'Y'),
(3, 500, 'X'),
(3, 600, 'Y');


SELECT *
FROM @BaseTable AS B
INNER JOIN (
    SELECT ID, X AS AmountX, Y AS AmountY
    FROM @Table1 AS T
    PIVOT (MIN(Amount) FOR Type IN ([X],[Y])) AS P
) AS T1
    ON B.IDKey = T1.ID;